'3r 



Ammmmmiammmm^mm&immmimm^ ' ^- 




^ ^ 



{0- 






LIBRARY OF CONGRESS. 



Chap. Copyright No. 

8helt:_'t^__V 5 



UNITED STATES OF AMERICA. 



NEW CENTURY SERIES 

OF 

ANATOMY PHYSIOLOGY AND HYGIENE 



BY 

HENRY F. HEWES, A.B., M.D. (Harvard) 

Teacher in Physiological and Clinical Chemistry, 
Harvard University Medical Scliool, Boston. 

WINFIELD S. HALL, PH.D., M.D. (Leipsic) 

Professor of Physiology, 
Northwestern University Medical School, Chicago. 



NEW CENTURY SERIES 
OF ANATOMY PHYSIOLOGY AND HYGIENE 



1. Oral Lesson Book in Hygiene. 

For Primary Teachers. 

2. The New Century Primer of Hygiene. 

First Book for Pupils Use 

3. Intermediate Physiology and Hygiene. 

For Fifth- and Sixth-Year Pupils, or Corresponding Classes in 
Ungraded Schools. 

4. Elementary Anatomy Physiology and Hygiene* 

For Higher Grammar Grades. 

6. Anatomy Physiology and Hygiene, ^ 
For High Schools. 



NEW CENTURY SERIES 
OF ANATOMY PHYSIOLOGY AND HYGIENE 



ELEME^^TARY ANATOMY 
PHYSIOLOGY AND HYGIENE 

FOR 

HIGHER GRAMMAR GRADES 

BY 

WINFIELD S. HALL, Ph.D., M.D. (leipsic) 

PROFESSOR OF PHYSIOLOGY, NORTHWESTERN UNIVERSITY MEDICAL 
SCHOOL, CHICAGO 



liabrary oi Congress 

pwo Copies Received 
m^ 6 1900 

Copyright entry 

SECOND COPY. 

Delivered to 

ORDtR DIVISION, 
NOV 17 19QQ 




NEW YORK •:• CINCINNATI -CHICAGO 

AMERICAN BOOK COMPANY 

1-- 



7141G 



INDORSEMENT 



We, the undersigned, have carefully exammed the school text-book 
entitled 

ELEMENTARY ANATOMY PHYSIOLOGY AND HYGIENE FOR 
HIGHER GRAMMAR GRADES 

by Professor Wixfield S. Hall, M.D., with reference to the following 
points : 

1. Eullness and accuracy of subject-matter relating to the nature and 
effects of alcoholic drinks and other narcotics upon the human system. 

2. Amount of matter on general hygiene. 

3. Presentation of matter with regard to its adaptability to the class 
of students for which it is designed. 

We are satisfied that on all of these points, as well as in the regular 
anatomy and physiology, the treatment is as complete as is required 
for a book of this grade, and fully in harmony with the results of the 
latest investigations. We therefore heartily indorse the book for Higher 
Grammar grades or pupils. 

A. H. Plumb, D.D. Mrs. Mary H. Hunt, 

Rev. Joseph Cook, LL.D. World's and National Superin- 

Daniel Dorchester, D.D. tendent of Scientific Tempeimnce 

William A. Mo^vry, Ph.D. Instruction for the Woman's 

L. D. Mason M.D. Christian Temperance Union, 

T. D. Crothers, M.D. 

Chas. H. Shepard, M.D. 

Text-hook Committee of the Ad- 
visory Board. 



Copyright, 1900, by 
American Book Company. 



HALL EL. PHYS. 

w. p. I 



PREFACE 

No field of school instruction has in recent years under- 
gone a more radical change in the method of presenta- 
tion than that of the natural sciences. This change has 
been a progressive one, and each year has recorded some 
advance. In all nature work in the grades as well as in 
all natural science work in the secondary schools and 
colleges the pupil is brought into contact with the material 
studied. This is effected either through demonstrations 
before the class or through laboratory or field work in 
which the individual pupil, under the direction and inspi- 
ration of the teacher, observes or experiments with the 
material. 

Physiology is a most important branch of the biological 
division of the natural sciences. Besides making a large 
part of both botany and zoology, it is set apart as a science 
by itself, devoted to the discussion of the functions of 
living matter. The nature work of the lower school 
grades leads naturally and logically to physiology, for 
which it forms a necessary basis. 

The subject of human physiology is the most important 
part of the nature study of the schools. It introduces 
the pupil to the physical house in which he must abide 
while he lives in this world and, with hygiene, to the 
essential conditions of highest attainment. 

With these principles in view, the subject of human 
physiology has been introduced with a brief treatment, 

5 



6 PREFACE 

largely experimental and practical, of the phj^siology of 
a growing plant. Through this means one can best show 
the interdependence of plant and animal kingdoms, and 
the unity and harmony of nature. 

Attention is called to the experiments suggested and 
described in the text. The appliances and material sug- 
gested are readily procurable; and the experiments de- 
scribed may easily be performed by any bright and 
energetic teacher. Taught in this way physiology be- 
comes a living and intensely interesting science. The 
problems given for solution by the pupils will tend to fix 
indelibly the hygienic principles involved in them. 

Especial attention is called to the lessons on Domestic 
Econoiny, This work has never failed to arouse the 
interest not only of the pupils, but of parents also, their 
feeling being that the school work in physiology is being 
made practical as life itself is and must be. This chapter 
and that on plant physiology is the work of Mrs. Winfield 
S. Hall. 

The author is indebted to Professor Wilson of Colum- 
bia University, to Professor Piersol of the University 
of Pennsylvania, and to Professor Williams of the Uni- 
versit)^ of Buffalo for several valuable figures. Acknowl- 
edgment is due also to Messrs. Lea Brothers, Philadelphia, 
for permission to reproduce several figures from the 
author's Text-hook of Physiology^ of which they are the 
publishers. 

WINFIELD S. HALL. 

Chicago, June, 1900. 



CONTENTS 
GENERAL PHYSIOLOGY 

CHAPTER PAGE 

I. Plant Physiology — How the Plant lives and grows . 11 
II. The Cells, Tissues, and Organs of the Body ... 27 

III. The Nervous System — How the Different Organs are 

made to work in Harmony 46 

IV. Narcotics — Their Nature, their Classes, and their Gen- 

eral Action upon the System 58 

SPECIAL PHYSIOLOGY 



y. Nutrition — How the Body is nourished . 

VI. Circulation — How the Nourishment is distributed 

VII. Respiration — How the Blood is purified 

VIII. How the Food is used in the Body .... 

IX. How the Waste Materials are thrown out of the Body 



76 
126 
164 
196 

206 



X. The Skin — How it is made and what it does — how to 

take care of it 211 

XI. The Special Senses — How one knows what is going on 

about him 225 

7 



8 CONTENTS 

CHAPTER PAGE 

XII. The Nervous System — The Brain, the Spinal Cord, and 

the Nerves 237 

XIII. The Muscles — How the Body moves .... 251 

XIV. The Skeleton — The Framework of the Body . . . 263 

Index . . . .271 



PHYSIOLOGY AND HYGIENE 

Physiology is one of the Natural Sciences. It tells how 
plants and animals live. It tells just what each part of 
the living being does, and how all of the parts work 
together. For example, it tells how the stomach digests 
the food we eat ; how the food is absorbed and dis- 
tributed to all parts of the body by the heart and blood 
vessels, and how each part of the body is nourished by 
the food tlius brought. 

Hygiene tells how to take care of the body. Every 
one wishes to have a healthy body. There are many 
things that injure the body, and many other things that 
make the body grow large and strong and healthy. 
Hygiene tells first, what is proper for the body, and 
second, what will injure it, and what should therefore be 
avoided. 

Physiology treats not only of man, but of all other 
animals, as well as of plants. Animals could not live 
upon the earth if the plants did not prepare food for 
them. One might think that man could live upon milk 
and eggs and meat if there were no plants to furnish 
vegetable food ; but a second thought makes it plain that 
the animals which furnish us w4th milk, eggs, and meat 
live upon vegetable foods, such as grass and grain. Thus 
we are all dependent finally upon plants. 

If one understands something of how plants live, that 
is, of Plant Physiology^ it is much easier to understand 
Animal Physiology and Human Physiology, We shall 

9 



10 PHYSIOLOGY 

begin our study of physiology by the study of how a 
plant lives and grows; then we shall study how the cells 
and tissues, of which the human body is built, live and 
grow, and the part which they play in bodies. This part 
of the general science of physiology is called Greneral 
Physiology, 



GENERAL PHYSIOLOGY 



CHAPTER I.— PLANT PHYSIOLOGY— HOW THE 
PLANT LIVES AND GROWS 

1. THE PLANT AND ITS NEEDS 

Here is a kernel of corn that is dry and hard, and here 
is another which has been in water for a few days. No- 
tice what a change has taken place in those few days. 
The little dried-up kernel has become large, full, and soft. 






Fig. 1. — a, a dry kernel of corn, h, a soaked kernel, c, soaked kernel from 
which a thin slice has been cut. cZ, soaked kernel cut through along the line 
ah, (6). e, soaked kernel cut through along the line cd, (5). The skin of 
the kernel is peeled up and one can see the plantlet lying in its little bed 
of food. 

Inside the change is still greater. If one opens a dry 
kernel, he will see in the midst of the white part a softer, 
yellow part which, in the soaked kernel, has become much 
larger and is plainly a little plant (Fig. 1). 

Here is still another seed that has been in the wet earth 
in a warm place for five or six days, and in this we see the 

11 



12 



PHYSIOLOGY 



perfect little plant partly within and partly without the 
kernel (Fig. 2, a). What suddenly started this little 
plant to growing after lying asleep all winter ? What 
waked it up ? 

It could not have been the water alone, for the kernels 
which Avere put in damp soil or water and set in a cold 
place showed no sign of life. Nor could it have been 






Fig. 2. — The corn plant growing from the kernel, a shows the size of the 
plant at one week, h shows the size at ten days, and c at two weeks. 

heat alone, for those that were put in a warm window 
without water still slept on. But when we gave them 
both heat and moisture, they awoke and began to grow. 
The growth, however, would soon stop if the plant had 
no food, so nature has put the food where the plant can 
get it most easily. 



PLANT PHYSIOLOGY 13 

The white part and the yellow part of the kernel are all 
the food which the plant needs until it is old enough and 
strong enough to earn its own living. But even with all 
the moisture and heat and food which it needs, a plant 
cannot be healthy without one thing more. 

You have seen a potato growing in a dark cellar, and 
have noticed its sickly, yellow color and long, weak 
shoots ; perhaps, too, you have seen a spot on the grass 
where a board has lain for several days and which Avhen 
removed showed the grass with yellow blades instead of 
green ones. 

Without light there could be no green color in the 
leaves nor strength and vigor in the plant ; without food 
the plant could not grow, and after living for a time upon 
its own tissue, it would die ; without moisture the plant 
would wither and dry up ; without warmth, the light, 
food, and moisture could not do their work. 

After the plant has started to grow, it grows in two 
directions, one part pointing up and becoming the stem, 
and the other pointing down and becoming the root, and 
whichever way the seed is planted, the stem will turn 
upward even if it has to make a complete turn to get 
started in the right direction. 

If we look at the seed after the plant has been growing 
for two weeks, we shall find there is little of the seed left 
within the shell, for the plant has eaten all the stored-up 
food (Fig. 2, 0. 

2. THE PLANT AIN'D ITS NEEDS {continued) 

We have seen that a plant needs food and drink, heat 
and light, but we have said nothing about another need 
that is quite as great ; that is, the need of the oxygen of 
the air. 



14 PHYSIOLOGY 

A plant not only eats and drinks, but it breathes. All 
plants breathe oxygen by day and by niglit. In plants 
that have leaves, the leaf is the organ of breathing ; in 
other plants the breathing is done by means of the body 
of the plant. 

Before we can understand the use of the oxygen we 
must know something further of the food and the work 
of the plant. A plant cannot eat solid food. It must 
take its food either as a liquid or as a gas. The liquid 
food is taken from the earth through the roots, and the 
gases are taken from the air through the leaves. At least 
half of the solid part of a plant body is carbon, and the plant 
must have a continuous supply of carbon to satisfy this need. 

There are several forms of solid carbon, such as coal or 
plumbago, but plants cannot eat solid foods, so that these 
forms cannot be used. The plant must take carbon in the 
form of gas, and this gas is called carbon dioxide. The 
plant can absorb this through the leaves and use it as a 
food. The most important food of a plant is carbon diox- 
ide, which is absorbed from the air by the leaves. 

Carbon dioxide is composed of carbon and oxygen. 
Carbon when alone is a solid like coal, or coke, or plum- 
bago. Oxj^gen when alone is a gas. The air is composed 
of a mixture of gases, of which oxygen comprises about one 
fifth of the whole amount. When oxygen and carbon are 
joined together they make a gas which is called carbon 
dioxide gas. Carbon dioxide forms a very small part of 
the air. The leaves absorb the carbon dioxide, and if the 
plant is in the sunlight, the green coloring matter in the 
leaf separates the carbon from the oxygen. The carbon 
remains in the plant as a part of the plant, while the 
oxygen escapes from the leaves as a gas. All of this 
wonderful process is a part of the plant's eating. 



PLANT PHYSIOLOGY 15 

To understand the way in which a plant breathes, we 
must study the subject of oxidation. Have you noticed 
that a fire which has been given plenty of coal will stop 
burning if we close the draught? If the draught is not 
perfectly closed, the fire will burn slowly ; but if quite 
closed, the fire will go out. It is plain that the fire needed 
something which it did not get. It had no oxygen. The 
coal cannot burn without the help of oxygen. This 
burning we call Oxidation, 

You have seen copper become tarnished and iron be- 
come rusted when exposed to the air. In both cases they 
have become oxidized. When the coal became oxidized, 
it was a quick process which we call rapid oxidation, but 
when the iron became oxidized it was by slow oxidation. 

Oxidation always produces heat. Rapid oxidation takes 
place in a short time with a great heat, while slow oxida- 
tion gives little heat during a long time. 

Heat may be used for warming houses, for cooking, or 
for producing power to move machinery. 

In the plant oxidation is used principally for power to 
do the work of the plant. The plant work is to push 
itself upward and to carry food from the ground to the 
highest point, and later to form the seed. It is the union 
of carbon and oxygen that gives the plant power to grow 
and to feed itself, and to make a ncAV plant. 

As the leaf is the organ for inhaling, it is also the organ 
for exhaling. This is done by means of the cells in the 
surface of the leaves. Let us remember, then, that every 
plant has work to do ; that to get the power to do this 
work it must oxidize its own substance with the oxygen 
of the air. Remember that oxidation of the substance of 
a living plant or animal is hreathing. All living things 
breathe in oxygen, which combines with the carbon and 



16 PHYSIOLOGY 

other substances to form carbon dioxide and other com- 
binations, such as water. After the carbon dioxide is 
formed it is ahvays thrown out of the animal body, but 
the plant leaves can use it for food when the sun shines. 

3. THE PARTS OF A PLANT 

We found the first need of a plant to be warmth and 
moisture, and found, too, that for days the plant could 
live upon nothing more than the food in the seed, with 
the water which it took in through the roots and the 
oxygen absorbed by the leaves from the air. 

We can easily understand from this that a large part 
of a young plant and some part of all plants is fluid. 

The fluid is in every part of the plant, and Avhen it 
is mixed with the food it becomes the sap. If you have 
tasted maple sap, you will remember that it was not like 
water, but was thicker and tasted sweet. That is because 
it has taken up the food of the plant, which it must carry 
to every part. 

Besides the liquid part the plant has another part, and 
this part we call the tissue, just as we call the substance 
of your dress or coat, the material, the fabric, or the 
tissue. As tlie tissues have different uses, we call them 
by different names. Those that are active and do the 
work of the plant, we call active tissues; those that sup- 
port the active tissues we call supporting tissues^ and those 
that cover and protect we call protecting tissues. Let us 
see if by thinking a little we can find which tissues belong 
to each division. 

We know that the work of this plant is done by the 
leaves, the root, and the stem. 

In all of these organs we find the living substance of 



PLANT PHYSIOLOGY 17 

the plant, which is called protoplasm. In the leaves it is 
green protoplasm, and in the stem and roots it is white 
protoplasm. All of the active tissues of the plant con- 
tain protoplasm, and are in the leaves, in the stem, and in 
the root. Most of the leaf is active tissue, but only a 
small portion of the stem and root is active tissue. The 
delicate root hairs contain protoplasm and represent active 
tissue. 

If you hold a leaf up and look through it toward 
the light, you will see the branching veins of the leaf. 
These veins serve a double purpose in the leaf ; (1) they 
support the active tissue of the leaf ; (2) they serve as a 
circulatory system along which the sap of the plant flows. 
The stem is made up almost wholly of supporting tissue, 
the only active tissue being the inner bark in the case of 
trees and shrubs. What is true of a stem of a tree is 
also true of a root. 

Protecting tissue is found upon every plant. The 
delicate, transparent skin which covers the little corn 
plant is its protecting tissue. The thick bark which 
covers the trunk and branches of trees and shrubs is their 
protecting tissue. Seeds have protecting tissue. The 
transparent skin so easily peeled off from a soaked kernel 
of corn is its protecting tissue. A nut has a hard, woody 
shell outside and a delicate brown skin inside, to protect 
it as it lies upon the ground all winter, waiting for the 
warm spring sunshine to wake it up. 

4. THE pla:n^t organs 

The tissues are but the materials of which the working 
part of the plants is made, and these working parts we 
call Organs, 

hall's phys. — 2 



18 rHYSIOLOGY 

We have already spoken of the leaf as the organ of 
breathing. On its surface both above and below are cells 
through wliich the oxygen passes. The leaf is formed of 
the three kinds of tissue. Inside is the living part or 
protoplasm, kept in place by the supporting tissues, the 
veins, and the whole leaf covered by the protecting tissue 
or skin. 

The work of feeding is shared by two organs, the leaf 
Avliich gets the gaseous food from the air, and the root, 
which gets the liquid food from the ground. This organ 
is composed of all three tissues. In large plants the main 
part of the root is supporting tissue, whose work is to 
hold it upright and firmly fixed in the ground ; but each 
large branch of tlie root has a thin coat of active tissue 
under its bark. In small plants like the little corn plant, 
the main part of the root is active tissue, composed of 
fine rootlets and root hairs, all filled with protoplasm and 
sap, and held in form and made strong by the cellulose, 
and covered and protected by the skin. 

The stem with its branches is the organ of form, and 
gives to the plant its shape. Without this part the plant 
could not grow tall, nor send out arms, nor have any of 
the beautiful forms which plants now take. It would lie 
flat and formless. 

The little corn plant which we have been studying has 
no other organs than the root, stem, and leaf, but in a 
mature plant there is still anotlier organ, the flower, to 
wdiich is given the highest work of the plant. The 
flower often adds beauty, color, and fragrance, but these 
things are not its real work. Its work is the making of 
a new plant of the same kind as the parent plant, and this 
is the crowning work of the whole plant. During the 
entire summer the leaves breathe in oxygen, the roots 



PLANT PHYSIOLOGY 19 

take in food, the veins carry it all over the plant body, all 
to give the plant strength to form the seed, which holds 
the sleeping plant for the following year. This work of 
making the seed and storing up within it the food for the 
young plant is so hard that it requires the help of the 
whole plant. But, as upon the seed depends the future 
good of the plant family, so each plant gives its work for 
the family good. 

It is so important that the plant prepare this seed and 
ripen it that if it cannot get the proper food and drink 
for growth and seed making, instead of using what it 
does get for its own growth, it sacrifices its growth and 
hastens to form the flower, which in turn will produce the 
seed and insure the next year's plant. 



5. THE SEED AND WHAT IT CONTAINS 

We have talked about the young plant and its needs; 
the growing plant and its needs ; the material from which 
the plant is made ; and the organs of the plant and their 
work. The most important organ we found to be the 
flower, and its most important work the making of the 
seed. Now we will talk about the seed and its material. 
Let us look first at the outside. Here is a seed that has 
been in water for three or four days (Fig. 1, page 11). If 
you use a penknife or a pin, you can loosen the outside 
part or skin. Look at it and see how tough it is. When 
it was on the kernel, it looked yellow, but when it is taken 
off, it looks colorless, and we now know that the color 
showed through and that the skin itself is transparent. 
Did you notice where the skin stopped? If you look 
carefully enough, you will see that the point of the seed is 
not covered. This is where the kernel is fastened to the 



20 PHYSIOLOGY 

cob. The skin is entire over the seed except over this 
point. 

Now we have taken off the skin and can see the body of 
the kerneh Look at the soaked kernel in which the parts 
have become swollen and are more easily seen. Now the 
little plant or germ can be loosened from the other part 
which is the plant food. In this seed that has been in the 
warm earth for five or six days the parts of the germ can 
be seen : the point which grows upward called the jjlum- 
ule, and the point which grows down called the radicle. 
Notice that what was a groove in the dry seed has filled 
out in this soaked seed, and in the seed that has been 
growing for a week we can see the root growing down- 
Avard from the pointed end of the seed, and the plumule 
growing upward from the middle of the side of the kernel 
in which the germ lay. Notice that on one side of the 
kernel there is a little bed of soft yellowish substance, in 
the midst of which the germ lies. This soft yellowish 
substance forms the first food of the little plant when 
it wakes up or sprouts in the spring. 

It will be interesting to find of what the seed and the 
germ are composed. 

The germ itself is composed largeh^ of protoplasm 
within thin cellulose walls and covered with a thin skin. 
Around this tender germ is a layer that is nearlj^ all pro- 
toplasm or proteid, and around that layer is the main part 
of the seed, which is starch. On each side of the ker- 
nel is a yellow part which contains the oil mixed with 
starch, and besides these materials are some minerals, 
such as salt and lime. 



PLANT PHYSIOLOGY 21 



EXPERIMENTS 

Get five cents' worth of iodine from the drug store. 
Dilute a part of this with water to a light brown color. 
Make a thin paste of laundry starch boiled with water. 

1. Put some of this paste in a drinking glass. Pour 
into the starch a little of the dilute iodine, and notice that 
the starch instantly tnrns to a beautiful blue color. This 
is called the iodine test for stai^ch. 

2. Put a little piece of lean meat in some of the strong 
iodine and notice that the meat turns brown. This is the 
iodijie test for proteid (see page 85). 

3. Cut some thin slices across a soaked grain of corn ; 
put them into any little shallow dish like a watch crystal 
or a butter dish, and notice that the white part of the 
kernel turns blue, showing the presence of starch ; and 
that the yellow part around the germ turns brown, show- 
ing the presence of proteid there. The germ itself turns 
brown becanse its protoplasm is one kind of proteid. 

4. Remember that the kernel contains the first food 
of the plant ; that this food is composed of starch, of 
proteid, and of oil ; that iodine turns starch blue and 
proteid brown. 

6. PLANT DIGESTION 

We know that as plants eat thej^ must have food, and 
that it must be in a form in which the plants can use it. 
As they can take no solid food, they must take all of their 
nourishment in the form either of gas or of liquid, and as 
many foods are not soluble in water, there must be some 
other process which changes them to a liquid form. This 
change is called digestion. 



22 PHYSIOLOGY 

Plant digestion is of two kinds, the digestion of the 
seed food^ which takes phice within the seed when the 
germ first wakes up and is feeding upon the food stored 
for it by the parent plant ; and the digestion of the soil 
food^ which the roots take up from the ground. 

It often hapjjens that both kinds of digestion are going 
on at the same time ; for example, when the wakened 
germ is living mainly upon the seed food, but has sent out 
one or two roots which bring in new material from the 
ground. As the roots can take only liquid food and the 
leaves only gaseous food, all changes in the food — or 
digestion — must take place outside of the plant body. 
Therefore the plant has and needs no digestive organs, 
but it does have digestive fluids, which it sends out to 
dissolve mineral matter or to change it into a liquid that 
can be taken up. 

We found a large part of the kernel of corn to be 
starch ; but if you were to examine the plant itself, j^ou 
would find no starch at all, and yet the germ plant lives 
upon that stored-up starch. It is evident then that 
some change must have taken place in the food. 

The foods that are found in seeds are either sugar, 
starch, oil, proteid, or cellulose, and all of these excepting 
the sugar must be digested before they can be used by the 
growing germ, and must be digested by some ferment. 

Do you know what is meant by a ferment? If you put 
corn or beans to soak in water for several days, 3^ou will 
find that the water becomes cloudy and has tiny bubbles 
on top ; that shows the work of a ferment. The same 
ferment will not digest all the kinds of food which seeds 
contain, but it requires one kind of ferment for oil, one 
kind for proteid, and another for starch and cellulose. 

Knowing that the food cannot be digested without a 



PLANT PHYSIOLOGY 23 

ferment, we naturally want to know where this ferment 
comes from and what it does. 

Let us go back to our first lessons, and we shall find that 
the plant germ sleeps in the seed until it is wakened by 
the action of the heat and moisture working together. If 
the germ has only water or only heat, it sleeps on, but 
when it has both in the right amount, it wakens. 

Bears and some other animals sleep during the winter 
in some warmly covered, dark place, neither eating nor 
drinking, and breathing but slightly. In the spring they 
waken and are so hungry that when we wish to express 
great hunger we say '^ as hungry as a bear." 

The germ within the seed also sleeps during the winter 
and wakens in the spring '^ as hungry as a bear." The 
mother plant had prepared for this hunger, and right at 
hand the wakening germ finds food. When the proto- 
plasm is wakened, it forms a ferment out of its own sub- 
stance, and this ferment digests the different foods. One 
kind of ferment digests the starch and cellulose, another 
kind digests the oils, and still another the proteid matter. 
After the food has been acted upon by the ferment it is 
ready for the plant to use in building up new parts. 

All the seed foods are digested in this way; but when 
the plant becomes old enough and strong enough to put 
out roots and to produce root hairs, then the plant uses 
another kind of digestion. The young plant carries on 
first the ferment digestion and then both kinds of digestion 
at once until the seed food is all used up. 

From the soil the plant takes up mineral food, of which 
it could get very little from the seed. 

A plant must have mineral matter to make it strong 
enough to stand upright. 

The minerals of the soil are solid, and are not soluble 



24 PHYSIOLOGY 

in water. If they were, the rains would wash them away, 
as they have washed the soluble salt, into the sea. 

Before minerals can be used as plant food they must be 
dissolved, and water will not do it. A way has been pro- 
vided by means of the root hairs. These root hairs make 
an acid whicli dissolves the grains of mineral matter which 
are held close to the root by the close-growing root hairs. 
As soon as the mineral is dissolved it is taken up by the 
root hairs, forms a part of the sap, and thence is carried 
all over the plant, where it is built up into the growing 
tissues, giving it that firmness which only mineral food 
can give. Some of the minerals used are quite common 
to us, as the lime and salt, but others quite as useful to 
the plant are not so well known to us. Some plants 
require more of one mineral, and others more of another 
kind, and this is one reason why different plants require 
different soils, and why it is better not to grow one kind 
of grain on a field year after year, but to change each 
year, thus having '' a rotation of crops." 

REVIEW OF PLANT PHYSIOLOGY 
The Plant Needs: 
Water 
Heat 
Light 



Gaseous, Carbon dioxide 



'j 



Oxygen 
The Plant Substance : f Of leaves 

... -r* X 1 J Of stem 

Active : Protoplasm i ^ „ 

^ 1 Of roots 

[ Of root hairs 

Supporting] J^^'^^'j^^^ 

Protecting : Skin 
Fluid: Sap 



Tissues : 



PLANT PHYSIOLOGY 



25 



Germ 



The Seed 



Digested by ferments secreted by plant germ. 



The Plant Organs : 

Leaf — organ for breathing and eating gas. 

Stem — organ for form. 

Root — organ for eating. 

FloAver — organ for producing a new plant. 

f Skin 

Plumule 
Radicle 
Sugar 
Starch 
Food \ Oil 

I Proteid 
[ Cellulose 

The Plant Digestion: 

Of Seed Food: 

Sugar 

Starch 

Cellulose 

Proteid 

Oil 

Of Soil Foods: Mineral matter digested by and absorbed by the 
root hairs. 

The Plant Economy : 

In Food stored for future use : 

Root 

\ Underground 

\ Aerial 
Seed ^ 

In Sleep during the Winter: 
Germ plant sleeps in seed. 
Adult plant sleeps. 

In eating Carbon dioxide. 

In breathing oxygen^ to get the energy which the plant needs to do 

its work. 
In changing mineral matter to vegetable tissue which is built up 

into the plant. 



Stem 



26 PHYSIOLOGY 

THE RELATION OF PLANTS TO ANIMALS 

Plants can digest minerals and change them to a form 
which the animal may use. 

Plants can eat carbon dioxide and water, and from 
these two substances can make sugar, starch, and oil, all 
of which are used by animals for food. 

Carbon dioxide is harmful to animals. As the plants 
consume it they make the atmosphere more healthful for 
the animals. Thus animals owe a great debt to the plants. 

Plants could not do these wonderful things if it were 
not for the sunshine. Thus we see that all nature is 
bound together into one great harmonious whole. 



CHAPTER II. -THE CELLS, TISSUES AND 
ORGANS OF THE BODY 

1. THE GENERAL STRUCTURE OF THE BODY 

Ix our study of the plant we found that its body is com- 
posed of organs; namely, the root, stem, leaves, and flowers. 
We found that each one of these parts of the plant body 
did a special part of the work which the plant has to do. 

In a similar way the body of every animal is composed of 
organs, and each organ has a particular work to do. The 
stomach is an organ whose work is to digest food ; the heart 
is an organ whose work is to pump the blood through the 
arteries and veins to the various parts of the body. The 
skin is an organ whose principal work is to protect the 
sensitive organs which it covers. 

The skin is a coat which the body always wears. In 
our cool and changeable climate the skin does not furnish 
enough protection, so that animals are furnished by Mother 
Nature with thick, warm coats of fur. But man is endowed 
with higher faculties than are the lower animals and, left 
upon his own resources, he makes for himself a thick, warm 
garment. He uses various materials, weaves them into 
fabrics, and then combines the fabrics into a garment. 
This garment, which we will suppose is a coat, is an organ, 
perfectly adapted to do a special kind of service for the 
man. 

Let us study this artificial organ, this coat, to see how 
it is constructed. It has a thicker outside and a thinner 

27 



28 PHYSIOLOGY 

lining. It may also have a middle layer to make it warmer ; 
that is, better adapted for its work. These layers of which 
the coat is composed are of fabrics ; that is, they are tissues. 
Any piece of cloth is a fabric or tissue. But how are 
these fabrics constructed ? If you examine a piece of 
cloth, you will find that it is made of threads woven 
together. If you examine a thread, you will find that 
it is composed of fibers. So that this artificial organ, 
a man's coat, is composed of fabrics or tissues ; the tissues 
are composed of fibers or bundles of fibers. 

In a similar way organs of the body are composed of 
various layers of tissues, and these in turn are composed of 
fibers, and bundles of fibers woven together. Some tissues 
are composed not of a woven layer of fibers, but of tiny 
globular, cylindrical, or rectangular bodies set side by side 
like the bricks or blocks in a pavement. These little 
bodies are called cells. 

So we may remember that the body is composed of 
organs, the organs are composed of tissues, and the tissues 
are composed of fibers or cells. 



2. THE CELL— WHAT IT IS AND WHAT IT DOES 

If one looks very closely at a slice of watermelon, he 
will be able to see that it is composed of tiny spherical 
globules lying side by side. They are almost too small 
to see without the help of a magnifying glass, and yet 
there are few plants which have larger cells, and most 
plants have smaller ones, too small, in fact, to be seen 
without a magnifying glass or a large microscope. 

The compound microscope was invented by a Hollander 
about three hundred years ago, but little practical use was 
made of it until a century later, when it began to be used 



CELLS, TISSUES, AND ORGxVNS 



29 



for the study of plant and animal tissues. It was very 
soon discovered that plant tissues are composed of little 
chambers which are spherical, cylindrical, cubical, pris- 
matic, spindle-shaped, or irregular in form. The early 
workers with the microscope chose the name cell for these 
little chambers. When it was discovered that the cells 








•Jtn 



v^>^- 



v*fs 



Fig. 3. — Diagram of a cell. [After Wilson.] Notice in this diagram of a 
typical cell the cell protoplasm, composed of cell plasm and cell lymph, and 
containing cell foods (C/.) and cell sap (C.8.). The large spherical nucleus 
has a true nucleolus {t.n.) , a false nucleolus (/m.) , a nuclear network (W.n.) , 
and nuclear lymph {N.L). c is the centrosome. 



were usually filled with a liquid, it was not known how 
important this liquid is. 

It was found out later that the liquid inside the little 
chambers is alive and is of far more consequence than the 
house in which it lives. The living substance is called 
protoplasm. Each little globule of protoplasm builds a 
wall around itself. At first this wall was called a cell. 



30 



PHYSIOLOGY 



i\^- 



t.n. 



Now we use the Avord cell for the globule of living proto- 
plasm together with its wall, 

Protophism is not a clear liquid like water, but is com- 
posed of a network Avhose meshes are filled with a clear 
watery fluid which is called cell lymph. The network is 
composed of threads or strands of a grayish, sticky sub- 
stance called cell plasm. The cell plasm is filled with 

minute grains. If the 
reader makes a care- 
ful study of Figure 3, 
he will find all of 
the parts mentioned 
above ; and in addi- 
tion to these he will 
find the spherical 
nucleus in the middle 
of the cell. The 
nucleus has a wall, 
a network whose 
meshes are filled with 
lymph, and holds two 
small spherical bod- 
ies, the true and the 
false nucleoli. 

If the reader now 
studies Figure 4, he 
will see practically 
the same parts in a different combination. This cell is 
a plant cell, and the cell sap is much more abundant in 
proportion to the protoplasm than is the case in the animal 
cell. All plant cells have walls. Sometimes the walls 
of a plant cell are very thick. 

Animal cells differ from plant cells in two very impor- 




p c/. 



~v-- pr. 



Fig. 4. — A typical i^lant cell. [Bastin.] 

Pr. shows the protoplasm, with its granules, 
but the network is not shown. The cell sap 
{c.s.) occupies a very large part of the cell. 
The cell food (c./.) makes a prominent addi- 
tion to the figures. N, the nucleus, contains 
the true nucleus {t.n.). This cell had seven 
boundary cells. 



CELLS, TISSUES, AND ORGANS 



31 



tant ways : (1) they have a very thin membranous wall 
or perhaps no wall at all ; (2) they have one or two small 
collections of cell sap, or more frequently no sap at all. 
Study Figures 5 and 6 and compare them carefully with 




4. 



c. 

D. 
E. 



F. 



Fig. 5. — Typical cells of animals and plants. 

A cell such as found in the lining of the windpipe. The little hairs on the 
top keep moving quickly in one direction and slowly in the other, and 
thus carry dust and mucus up to the throat from the lungs. 

A cell from the windpipe, or nose, or intestine. This kind of cell is called 
a goblet cell. It is full of clear mucus. From time to time the cell 
empties out its mucus. 

A cell from the stomach. This kind of a cell helps the stomach to digest 
the food. Its part of the work is to help make the gastric juice. 

One of the blood cells. 

A plant cell. Notice : the numerous vacuoles filled with cell sap (C.s.) ; the 
cell protoplasm (C.p.) filled with innumerable tiny granules; the little 
masses of cell food ((7./".) ; the large nucleus with its nucleoli and network. 
The cell has a heavy wall, and one can see where seven other cells join it. 

A typical animal cell [Wilson]. C.p., cell plasm ; C.I., cell lymph; C/., 
cell food ; C.s., cell sap ; W., nucleus ; n., nucleolus. 



Figures 3 and 4. Remember that the important part of a 
cell is the living protoplasm^ and that the protoplasm is 
composed of a network of cell plasm^ whose meshes are 
filled with cell lymph; that the cell contains the nucleus^ 
which has a network and nuclear lymph and contains one, 



32 



PHYSIOLOGY 



two, or three nucleoli; that there maj^ be little masses of 
cell food ; and small globules of cell sap ; and, finally, that 

the plant cell nearly always lias a 
thick cell wall while the animal 
cell usually has a very delicate 
membranous wall. 



THE CELL, AND WHAT IT 
DOES (continued). 








Fkom the preceding lesson we 
have learned something about the 
parts of a cell. It seems wonder- 
ful that all these parts can be 
found within an object too small 
to be seen without a microscope. 
When we learn of the work which 
the cell is doing and the part which 
it plays in the world, it will all 
seem like a fairy story, but all 
Fig. 6. — A typical animal cell, of the facts to be givcii here have 

Notice that in this cell all the , , t i- ^ 

parts except the cell sap may been observed many times by men 
be found. [Verworn.] ^yiio devote their livcs to the study 

of these problems. 
Every one has noticed the green powder which collects 
upon the tree trunks, fence posts, and stones or bricks 
which are in damp places out of doors. If one were to 
put a few grains of this green dust in a drop of water 
upon a glass and look at it with a strong microscope, he 
would find each grain to be spherical in shape, to have a 
transparent cell wall, and to be filled with a grayish mass 
in which may be seen many tiny green granules. These 
little spherical bodies are cells. Each one is a complete 



CELLS, TISSUES, AND ORGANS 



33 



plant (Fig. 7). Its green granules are the same as those 
which make the corn, wheat, grass, and trees green in 







Fig. 7. — Protococcus, a dustlike, one-celled green plant, seen as a powder 
upon the trunks of trees, upon fences, stones, etc. In 6, c, and d is shown 
the way in which the mother cell divides up into two, three, or more daughter 
cells. After division the cells may remain together in a colony, as in h or c, 
or they may separate, as shown in d. 




color. If one examines under a microscope a drop of 
water from a pool or pond that has been standing stag- 
nant for several weeks 
during the summer, he 
is sure to find little 
green bodies similar 
to the ones we have 
just studied. These 
are cells also. Some 
of them have little 
moving hairs whose 
whiplike motions pro- 
pel the cells through 
the water (Fig. 8). 
Each of these one- 
celled plants leads an 
independent life. Each 
receives the light and 
warmth of the sun in 
its green granules. 
Each eats carbon dioxide gas and water ; each makes 
sugar, and starch, and protoplasm. Each begins as a 
hall's phts. — 3 




a h c 

Fig. 8. — One-celled water plants. One of them 
(«) has a little whiplike tail whose rapid 
movements propel the plant through the 
water something like the swimming of a 
tadpole. But they are so small that hun- 
dreds of them would have plenty of room 
in a drop of water, h and c are Desmids, 
chiefly noticeable for their beauty. 



34 



PHYSIOLOGY 



very small cell and grows larger and larger until it 
becomes a grown up or adult cell. Each one raises 
a family of daughter cells, as they are called. Finally 
each one gets old and dies. 

If one examines under a microscope a drop of water 
which he has taken, with a glass tube, from the slimy 
bottom of a stagnant pool, he is likelj^ to see little glob- 
ular or irregular grayish bodies, which keep changing 







Fig. 9. — An Amoeba, a shows the animal in a resting stage or asleep, b shows 
it as it starts out for something to eat. c and d show it coming in contact 
with a diatome and swallowing it through a mouth made for the occasion. 



shape and creeping across the glass on which the water 
lies. These curious objects are living creatures which 
belong to the animal kingdom. 

These little animals are called Amoehce, When an 
amoeba sleeps or rests, or when it is afraid, it draws 
up into a ball (Fig. 9, a). When an amoeba gets hungry, 
it projects feet right out of its side anywhere. With 
these false feet, as they are called, it creeps over the 
surface on which it rests until it comes to some object 
which it can eat, when it opens a mouth anywhere and 
takes the object in. The figure (Fig. 9, 6?) shows the 
amoeba in the act of swallowing a little one-celled plant. 
The amoeba grows larger as it grows older. After a 



CELLS, TISSUES, AND ORGANS 



35 



while it becomes an adult mother amoeba ; then it di- 
vides into two daughter amoebae. This process of raising 
a family is shown in Figure 10. 

Mention has already been made of the movements made 
by the plant (Fig. 8) and by the hungry amoeba. If one 
breaks off a slimy spray of a fine water plant and looks at 




Fig. 10. — An adult amoeba dividing into two daughter amoebse. Notice that 
each daughter has a share of the parent nucleus, as well as a share of the 
parent protoplasm. [Hall.] 



it under a microscope, he is likely to find some interesting 
little animals like those shoAvn in Figure 11. The most 
noticeable feature of these one-celled animals is that when 
everything is quiet they extend the stem to its full length 
and open their bells as wide as possible. Each of these 
animals has a row of hairlike arms or tentacles called 
cilia around the bell. When anything disturbs, startles, 
or irritates them, they instantly fold the bells in, draw the 



36 



PHYSIOLOGY 



cilia together, and contract the stem until they occupy 
the smallest possible space. This all shows that they 

are sensitive^ and that 
they can respond to a 
stimulus. 

Remember that all 
cells begin as small 
young cells and grow 
up to adult life by eat- 
ing; that all cells have 
to work for their living; 
that all cells breathe in 
oxygen and breathe out 
carbon dioxide gas ; that 
all cells are sensitive to 
things or conditions out- 

FiG. 11. — A Stentor {a, b) and a Voi^ticella - ^ ^ ,^ -i i 

(c, c7). a and c show these little one-celled SlCle 01 tliemselves ; and 

animals relaxed, with the bell open, and that many cells have the 

the little hairs around the mouth of the „ 

bell waving the particles of food into the pOWer 01 motlOll. 
open mouth of the bell, h and c show 

both animals contracted after something i • i 

has startled them. [Verworn.] plants and animals con- 
sist of only one cell. 




Remember that many 



4. TISSUES — HOW THEY ARE MADE AND WHAT 
THEY DO 



If you will turn back to Figure 7 and Figure 10, jovl 
will see that full-grown plant cells and full-grown animal 
cells divide into two or more young cells which begin life 
as small, restless, hungry cells which forage for food, eat 
ravenously, and grow rapidly into adult cells. In the 
amoeba the daughter cells separate, and each one goes off 
by itself where it must fight its own battles single handed. 



CELLS, TISSUES, AND ORGANS 



37 




There are man)' little water animals larger and stronger 
than the anKpba, which hunt for it, and when they find it 
devour it as a tender 
and nourishing mor- 
sel. The little green 
plant, Protococcus, 
shows us something 
new. Notice that in 
h and c (Fig. T) the 
daughter cells do not 
separate, as do those 
in 6?, but remain to- 
gether in a little 
family or colony. 
Figure 12 shows a 
plant of a higher 
order than the pro- 
tococcus. It is placed 
in a higher rank be- 
cause it is better fitted for the varying conditions of life. 
How is it better fitted ? Just as a colony of men is better 
fitted than one person to meet the dangers of a pioneer 
life, so is a colony of cells better fitted to meet the dangers 
which exist in the pond or on the tree trunk. In union 
is strength. The enemy strong enough to overcome an 
individual easily does not dare to attack a colony, and 
thus the dangers are lessened. There is another great 
advantage in colonial life. Notice that both the colonial 
animal and the colonial plant have two kinds of cells. 
The outer cells of the little plant in Figure 12 are pro- 
vided with delicate whiplike arms. With these arms the 
outer cells move the whole colony through the water or 
along the bottom of the pond or aquarium. The outer 



Fig. 12. — A little water plant composed of a 
colony of cells held together by a mass of 
gelatinous substance. [Verworn.] 



38 PHYSIOLOGY 

cells of the little sponge are similarly provided with whip- 
like arms, whicli have little cups into which they may 
withdraw for protection (Fig. 13). 

In a similar way the individuals in a colony of men do 
not all perform the same kind of work, but some will be 
builders, others will groAv grain and vegetables, and so 
on, each being especially fitted for his own work. 




Fig. 13. — A little animal, a kind of sponge, composed of a colony of cells held 
together by a mass of gelatinous substance. [Verworn.] 

Nature has used this principle of the colony and has 
produced all the higher plants and animals in harmony 
with the principles which govern a colony or community. 
The largest animal or plant is only a great colony of cells, 
each cell having its special work to perform. In a large 
colony or community of people, there will be a great 
many who devote their Avhole energy to producing the 
things which serve for nourishment or nutrition ; others 
will devote themselves to transportation, carrying nour- 
ishment and building material from one place to another ; 
others will be builders ; others will be the protectors and 



CELLS, TISSUES, AND ORGANS 



39 



serve in the army or on tlie police force. In a similar 
Avay the cells of the digestive system of an animal are 
engaged in preparing food ; the cells of the circulatory 
system are engaged in transporting this food to all parts 
of the body where it is needed ; the cells of the cuticle, 
hair, nails, are engaged in j)i'otecting the body. 

Any group of similar cells engaged in a similar work 
makes a tissue. Tissues may be composed of cells alone 





Fig. 14. — A thin slice of cartilage or gristle. Slice a shows the clear, brittle 
cartilage which is found at the ends of bones. Slice h shows the yellowish, 
tough cartilage which forms the cushions between the vertebrae. [From 
Miller's Histology.'] 



or of cells together with substances which the cells have 
formed and which they use in their work. A transporta- 
tion system consists not only of the men directing it, but 
of their railroads, trains, and so forth. So a tissue may 
consist of more than the simple cell bodies. Figures 12 
and 13 show between the cells a gelatinous substance 
made by the cells for the purpose of holding the cells 
together in a colony. This gelatinous substance together 
with the cells makes a tissue. The little plant and animal 
shown above (Figs. 12 and 13) are really tissues, but 
more complex plants and animals may be composed of 
many tissues. 



40 PHYSIOLOGY 

Figure 14 sIioays a thin slice of cartilage or gristle as it 
would look under a high-power microscope. Cartilage is 
a tissue of the human body used princij)ally in the joints. 

Figure 15 sliows connective tissue fibers woven into a 
network. In both the cartilage and the connective tissue 
the cells are of much less importance than tlie substance, 




Fig. 15. — Connective or supporting tissue taken from beneath the skin. 
Notice that there is a loose network of wavy bundles of fibers, also a net- 
work of threadlike fibers. All of these fibers were formed by the cells which 
you see lying in the meshes. [Schaefer.] 

matrix, or fibers, which they have formed. In fact, the 
work of the connective tissue cells is done Avhen they 
have made the connective tissue fibers. The fibers do 
the work of the connective tissue. 



5. ORGANS — HOW FORMED AND HOW GROUPED 

Ix a previous lesson the coat was likened to an organ, 
and its various fabrics (outside, lining, and padding) to 
the various tissues which compose an organ. The stom- 
ach is an organ. It is composed : (1) of a smooth, shiny 
outer layer ; (2) of a muscular layer ; (3) of a layer of 
loose connective tissue, like that shown in Figure 15 ; 
and (4) of a layer of cells set close together like the 



CELLS, TISSUES, AND ORGANS 



41 




blocks or bricks in a pavement. The work of the stomacli 
is to help digest the food. To do this work of the stom- 
ach, the inner layer of 
cells is needed to make 
the digestive fluid. 
The connective tissue 
is a supporting tissue. 
The muscle tissue 
causes the churning 
movements which the 
stomach makes when 
it is digesting food ; 
and the outside, Fig. 16. —Diagram of a slice of the wall of the 

smooth, shiny layer stomach ^ ^, mucous membrane; ^, Sub- 
, '^ ^ mucosa; (7, muscular coat ; D , fibrous coat ; 

' is supporting tissue E, internal circular layer of muscular fiber ; 
which mves form to ^^ external, oblique, and longitudinal mus- 
& cular layers. 

the stomach and cov- 
ers the muscles to protect them. So we see that the 
stomach is an organ with a general work to do, and that 
it is composed of tissues, each of which has a special part 
of the work. Now each one of the tissues is composed of 
cells which are practically all alike. For example, all of 
the cells of the muscular coat are alike and all work to- 
gether doing the same kind of Avork. All of the cells 
which make up the inner lining of the stomach are alike 
and work together to make the fluid which digests the 
food in the stomach. Figure 16 shows how a piece of 
the wall of the stomach would look under a microscope. 

The intestine is an organ. Its general work is to assist 
in the digestion of food. It is composed of four layers of 
tissue quite like the stomach. 

The pancreas (^pan'kre-as) is an organ. Its work is to - 
make a fluid which is sent through a little tube into the 



42 



PHYSIOLOGY 



intestine, Avliere it helps to digest the food. The pancreas 
is a glandular organ. Glandular organs are composed of 
many tubes lying close together. Each tube is surrounded 

by cells set together like blocks 
in a pavement. Figure 17 
shows a very simple gland. 
The pancreas is composed of 
many hundreds of crooked 
tubes, all lined with cells which 
make the digestive fluid. 



SYSTEMS OF ORGA^^S 




Fig. 17. — Diagram illustrating 
the plan of a gland. A, cells 
which line the gland ; B, blood- 
vessels; C, connective tissue. 
[From Miller's Histology.] 



We have been studying or- 
gans. We found that the stom- 
acli is a digestive organ ; the 
intestine is a digestive organ, 
and the pancreas also. There 
are other organs which assist in digestion : the mouth, 
with its teeth, tongue, and salivary glands, prepares the 
food for swallowing ; the esophagus Qe-sof^a-gus^ is the 
tube which carries the food to the stomach. Then 
the stomach and intestine hold the food while it is being 
digested by the fluids made in the stomach, intestine, and 
pancreas. All of these organs work together in the prep- 
aration and digestion of food, and we call them collectively 
the Digestive System, 

In a similar way there are numerous organs which all worli 
together to carry the blood all over the body. All of these 
organs taken together are called the Circulatory System^, 

Tlie organs which work together to bring oxygen into 
the body and carry the carbon dioxide out of the body 
make the Respiratory System, 



REVIEW OF CELLS, TISSUES, AND ORGANS 43 

Remember that the Qreneral kinds of work — the sfen- 
eral functions — of the body are performed by systems 
comprising several different organs ; that each organ has 
a particular part of a general function to perform ; that 
every organ is composed of tissues ; and that each tissue 
assists the organ to do its work. 

HYGIENIC CONDITIONS OF THE CELLS 

In every normal cell is to be found matter in three con- 
ditions — the matter that is actually living, that which has 
lived, and that which is about to live. To maintain these 
three states there must be constant activity, a constant 
merging of the first state into the second, and the second 
into the third. Anything that interferes with this activ- 
ity interferes wdth the health of the cells, with the Avork 
they have to do, and with the vitality of the tissues which 
they compose. 

The cells cannot work actively if deprived of a sufficient 
amount of the oxygen of the air. Whoever sits or sleeps 
in close, unventilated rooms decreases the healthful activ- 
ity of the cells. Whoever takes an insufficient amount of 
exercise does the same thing, because this leads to a slug- 
gish flow of the blood which brings oxygen to the cells. 

Some substances, when brought into contact with the 
living matter of the cells, stimulate or increase their ac- 
tivity, other substances check this, and others stop it 
altogether. The checking, if continued, results in the 
death of the cell. A few cells may die without causing 
the death of the tissue. 

The effect of various substances upon the living cell 
may be watched under a microscope. If bathed with a 
proper food substance, the cell may be seen to expand and 
grow and move more actively. If bathed in an astringent 



44 PHYSIOLOGY 

substance like tea, it shrinks up into a ball, and ceases its 
movements until restored. If bathed with a liquid con- 
taining a very small proportion of alcohol, its activity will 
cease, and, unless the proportion is very small, it cannot 
be again revived. 

Plant protoplasm is so much like animal protoplasm as 
to render it likely that what will injure the one will injure 
the other also. Alcohol, in even small proportions, does 
injure plant protoplasm. 

The London Lancet for June 16, 1900, quotes Dr. J. 
J. Ridge as saying that healthy cell life, both of plants 
and of animals, is impossible in the presence of minute 
quantities of alcohol. This is because the cells cannot 
then take in enough oxygen, and cannot cast out the 
waste matter from their bodies. 

'' Even in extremely minute proportions, alcohol pre- 
vents or retards the sprouting of seeds, and kills or stunts 
the growth of the seedlings that are developed. As small 
a proportion as one of alcohol in eight hundred of water 
will have a powerfully poisonous effect. The moderate 
drinker of alcohol dissolves in his blood, and by means of 
the blood conveys to the living active cells of his brain, 
liver, kidneys, and other organs, a much greater propor- 
tion than one in eight hundred, at least once and often 
several times each day.''^ 

" Alcohol exerts an exceedingly harmful action on rap- 
idly growing tissues, interfering with their nutrition, and 
preventing the development of their proper action. In 
old age, when the tissues are on the down grade, and are 
subject to various degenerations, alcohol, in most cases, 
merely accelerates the process of decay." ^ 

1 Professor William Carter, M.D. 

2 Professor G. Sims Woodliead, Cambridge, England. 



REVIEW OF CELLS, TISSUES, AND ORGANS 45 

Tobacco injures the cells of the body by making them 
less active. 

When we review what has been said about what alco- 
hol does to living cells, we find : — 

(1) The living matter in the cells of plants requires the 
same things for its healthy action as does the living 
matter in the cells of animals. 

(2) What will injure growing plant cells will usually 
injure growing animal cells. 

(3) Alcohol as found in whisky, rum, wine, brandy, or 
beer, even when very much diluted, will stop all healthy 
activity, and growth of sprouting plants. 

(4) In the same way, alcohol in its various forms, and 
much diluted, will stop, or at least injure, the healthy 
activity of the cells of a young person. 

(5) Alcohol is injurious to healthy cells, tissues, and 
organs of both plants and animals, old or young. 

REVIEW OF CELLS, TISSUES, AND ORGANS 

1. Plants and animals are composed of tiny particles of living sub- 
stance. These particles are of various shapes and sizes, and are called 
Cells. Some cells are spherical, some are cylindrical, some are thin 
and flat, some are threadlike. 

2. Cells are composed of Protoplasm which is made up of a network 
of living, moving Cell plasm, whose meshes are filled with the watery 
Cell lymph. 

3. The Cell must have food to eat and air to breathe ; it can feel 
and it can move. The cell is small when young ; it grows, and ivorks, 
and finally dies. 

4. Cells are grouped together in Tissues. Some stand side by side 
like the blocks in a pavement ; some overlap like the shingles upon a 
roof, and some are woven together like the threads in a fabric. 

5. Tissues form Organs. Each Organ has a special work to per- 
form ; and the tissues assist in doing the work. 

6. Organs are grouped into Systems of Organs. 



CHAPTER III. — THE NERVOUS SYSTEM — HOW 
THE DIFFERENT ORGANS ARE MADE TO 
WORK IN HARMONY 

1. THE NEED OF HARMONY IN THE WORKING OF 

THE ORGANS 

We have found that the plant or animal body is a 
colony of cells. We have found that, like a colony of 
men, some of the individuals (cells) have one kind of 
work and some another. Another very important point 
of resemblance between the two colonies is the need for 
harmony of action between the different individuals (cells) 
of the colony. 

When there are only a few hundred individuals in a 
liuman colony, there is always some central controlling 
agency. It may be a patriarch, a chief, a sheik, a king, a 
czar, or a president, but in every case there is a controlling 
head to make decisions as to what to do next. This princi- 
pal controlling agency is always supplemented by a body 
of individuals whose work is to assist in making decisions, 
or to announce the decrees or decisions to remote parts of 
the colony. 

If a community of people were without these most 
important functionaries, there would be no harmony of 
action in time of need or of danger. Who has not seen 
an excited company gathered at the burning of a neighbor's 
house — everybody giving orders which nobody obeys ; 
everybody bus}^ but little or nothing accomplished. 

46 



THE NERVOUS SYSTEM 47 

Presently a captain of police or head of a fire company 
appears upon the scene; he is experienced in the control 
of fires and of men. He begins to command ; everybody 
gives heed and obeys. There is unity of action, tliere is 
harmony in the means used, both in the time of doing a 
particular thing and in the extent, to which any particular 
work shall be done. 

Think how impossible it would be to accomplisli the 
work of a great railroad company, if there were not a 
central office in which plans are laid, decisions made, and 
commands issued. Through immediate and explicit obe- 
dience to these commands every individual, and every 
group of individuals employed by the company work 
together harmoniouslj^ for the accomplishment of the 
important work which they are undertaking. 

In a strikingly similar way the great number of cells 
(individuals) which make up the human body must be 
controlled by some central power, or they will work at 
cross purposes. 

Suppose the stomach should make the digestive fluid at 
a time when there was no food in the stomach, and suppose 
the glands of the mouth which make the saliva should not 
work when the mouth was chewing the food. Then sup- 
pose after the chewed food started 'down the esophagus, 
that tube should stop contracting ; the dry food would 
stick in the esophagus and have to be washed down with 
water. But the stomach, having already made its fluid, 
and passed it on into the intestines, would be dry, so that 
the food would be moistened only by the water which 
came into the stomach with it. Then the food would not 
digest, but would ferment in the stomach and would make 
the person sick. 

So we see the. absolute necessity of having some con- 



48 PHYSIOLOGY 

trivance for controlling the action of all of the organs, 
systems of organs, tissues, and cells. When this control 
is perfect, the body remains in good health ; but when 
some portion of the body, even if it be ever so small a 
portion, fails to obey the commands issued by the central 
governing organ, the whole system is likely to become 
deranged and the body become sick. 

The central governing organ of the human (or other 
animal) body is the brain. The brain is assisted by the 
spinal cord which lies within the backbone, and by vari- 
ous organs which collect news for the brain and carry the 
messages for it. The brain with the spinal cord and the 
nerves makes the general nervous system, 

2. THE GE:N^ERAL STRUCTURE OF THE NERVOUS 

SYSTEM 

In bringing harmony of action among those who work 
for a great railroad corporation, a great army, or other 
large community of individuals having common interests, 
two things are necessary ; (1) a central controlling power; 
and (2) communication from the center to all of the dis- 
tant parts of the company, armj^, or community. 

In controlling the movements of trains upon a railroad 
system, messages are sent along telegraph wires to con- 
ductors hundreds of miles away, directing them what to 
do in order that there may be no accident. If something 
unexpected happens in some part of the system, a message 
is sent to the controlling center, where action is taken to 
adapt the movements of trains to the new conditions. 

In a strikingly similar way the animal body possesses a 
central controlling power in the brain. The brain is in 
constant communication with all parts of the body. Mes- 



THE NERVOUS SYSTEM 49 

sages are continually being sent to all parts of the system. 
Telegraphic messages are sent over wires ; the brain sends 
and receives its messages over fibers which are as fine as 
as those of a spider's web. 

The telegraph wire is not a part of the telegraph opera- 
tor, but the nerve fiber is a part of tlie operator whose 
station is in the brain or spinal cord. This operator is a 
nerve cell. The brain and spinal cord are composed of 
nerve cells with their fibers. Every nerve cell has long 
fibers over which it sends messages away to other nerve 
cells, and every nerve cell has at least one nerve fiber 
or arm (most have several) through which it receives 
messages. 

When several telegraph wires are to go side by side for 
a long distance, they are frequently bound together into a 
cahle. In a similar way the nerve fibers which leave any 
one part of the brain or cord to go to the same general 
region of the body are bound together into a cable or, as 
it is called, a nerve trunk. Nerve trunks contain, not sev- 
eral only, but many hundreds of the fine nerve fibers. 
Along the course of the nerve trunk branches are given 
off, which distribute the nerve fibers to different muscles 
and organs or to different parts of the skin along the 
course of the main trunk. 

Figure 18 shows the general form and distribution of 
the nervous system. The brain, within the skull, is the 
controlling center. The spinal cord, which passes down an 
arched-over canal in the vertebral column, consists mostly 
of nerve fibers wliich carry messages to and from the nerve 
cells of the brain. There are relay stations all along the 
spinal cord where messages are received and sent out on 
their way to and from the brain. 

All of the white lines branching off from the spinal cord 

hall's phys. — 4 



50 



PHYSIOLOGr 




Fig. 18. — The nervous system. .4 , cerebrum ; 5, cerebellum; (7, the sciatic 
nerve trunk, giving off branches as it passes down the leg. 



THE NERVOUS SYSTEM 



51 



represent trunks of 
nerves which lie be- 
tween the muscles or 
under the skin of the 
bocl}^ and limbs. But 
there are also nerve 
trunks which pass from 
the spinal cord inward 
to the body cavity, to 
the thorax and abdo- 
men. There is a double 
line of ganglia along the 
back side of the body 
cavity. A ganglion is 
a relay station made 
up of numerous nerve 
cells. These ganglia 
are about as large as a 
pea or bean. Each of 
the ganglia in the dou- 
ble row, mentioned 
above, receives a bun- 
dle of fibers from the 
spinal cord. Some of 
these fibers bring mes- 
sages to the ganglia 
from the brain or spinal 
cord, while some of 
them carry messages 
from the ganglion to the 
brain or cord. 

Each ganglion in the 
chain sends out nerve 



YO^^oU^ 




Fig. 19. — The sympathetic nervous system. 
Note the branches (I, II, III, etc.) from 
the spinal cord to the row of little globular 
masses or ganglia. A corresponding row 
on the right side sends branches to the 
large central ganglia of the abdomen, the 
splanchnic {s) , and the mesenteric (m). 



52 PHYSIOLOGY 

trunks to organs of the thorax or abdomen, or to large 
ganglia in the midst of the abdomen. These large central 
ganglia serve a purpose similar to that of the central 
exchange of a telephone system. They serve to put the 
organs into either direct or indirect communication with 
each other. Through this direct or indirect communication 
the activity of one organ is responded to by a correspond- 
ing activity of another. For example, the presence of 
food in the stomach stimulates the stomach to begin to 
make the churning movements, and to form the digestive 
fluid. This activity of the stomach causes the pancreatic 
gland to begin its work of making digestive fluid for the 
intestine to use in its digestive work. This nervous 
communication between the different organs of the body 
enables them to work together toward common ends har- 
moniously. Because of this sympathetic communication 
between the internal organs which these nerves and 
ganglia make they are together called the sympathetic 
nervous system. Remember, however, that the sympa- 
thetic nervous system is simply a part of the general 
nervous system. 

Through the influence of the sympathetic nervous sys- 
tem, the derangement or disease of one organ may cause 
the derangement or disease of other organs. 

3. REFLEX ACTION AND HABIT 

In the previous lesson we learned that there are relay 
stations along the spinal cord. A message sent from the 
brain to the muscles of the arm starts from a nerve cell 
in the brain and follows its fibers down the spinal cord 
to a place opposite the shoulders, where the fiber ends in a 
little tuft of branches which lie among the short branches 



THE NERVOUS SYSTEM 53 

of a nerve cell in the cord. The message is communicated 
from, the branches of the fiber from the brain to the short 
branches of the nerve cell in the cord, and this cell sends 
the message along its fiber to the muscles. If the message 
tells the muscle on the front of the forearm to contract, 
the fist will double up. When one's brain sends such a 
message as that, one is conscious of it. Furthermore, one 
knows it before the brain sends out the message ; so that 
one can send it or not just as he chooses. 

This kind of action is called Voluntary Action^ because 
one may do it or not just as one wills. 

Why does one will to make a certain motion ? Suppose 
one were hungry and had before him a piece of food. 
The eyes, and perhaps also the nose, would send messages 
to the brain ; that is, one would see and smell the food. 
These sensations in the brain would arouse a desire for 
the food. Messages would be sent to and fro from one 
cell to another in the brain ; that is, one would begin to 
think about the food and his need for it, and finally, per- 
haps in a very few moments, one would decide to take the 
food. Messages would be sent to various muscles ; the 
arm would be extended, the food grasped, the arm flexed, 
and the food carried to the mouth, which would be opened 
to receive it. This is a very brief and imperfect descrip- 
tion of all that takes place in the nervous system under 
such conditions. To describe it accurately and completely 
would require many pages. Before one stops to think 
about it, however, it seems to be the simplest thing in the 
world ; so simple, in fact, that a little baby too small to 
talk or to walk will perform every portion of the series of 
motions with faultless accuracy and grace. 

Let us take another example. Suppose that one takes 
hold of a very warm iron poker, one end of which is in 



54 PHYSIOLOGY 

the fire. There are nerves of sense in the skin of the 
hand ; messages are sent along the fibers to nerve cells 
which lie just outside of the spinal cord. From the cell a 
fiber carries tlie message into the cord and communicates 
it to another cell whicli carries it to the brain. When 
the message reaches the brain, one becomes conscious of 
the heat of the poker. Let us suppose that the heat is 
sufficient to make one uncomfortable, and fear that the 
hand may be burned if the hand is not removed. Mes- 
sages will be sent down the cord to the proper muscles, 
and the hand withdrawn. There we have another ex- 
ample of voluntary motion following sensation. 

Now when the message of sensation enters the cord on 
its way to the brain, it follows a branching fiber, only one 
portion of which goes to the brain. The other portion 
passes across the cord, directly or indirectly, and com- 
municates with the nerve cells which control the muscles 
of the arm and hand. 

Suppose one touches a very hot object, the message 
which is sent to the cord on its way to the brain is 
instantly communicated across the cord, and the nerve 
cell of motion, without waiting to hear from the brain, 
sends the message back to the arm, causing it to contract 
and remove the hand from danger. This saves time and 
frequently decreases the danger done to a part of the 
body. 

An instant later the brain is fully conscious of all that 
has happened. One knows that the hand has been burned, 
and that it was jerked away before the brain was con- 
sulted ; but one always approves of the action. 

This intervention of the cells of the spinal cord in cases 
of emergency is called reflex action. But the term has a 
somewhat wider application than simply to cases of 



THE NERVOUS SYSTEM 55 

emergency. When one is learning to perform a new 
movement or series of movements, such as walking, skat- 
ing, riding a bicycle, writing, and playing a musical 
instrument, each movement is a voluntary one.^ The 
Avhole attention is required to direct the movements of 
the body and its different parts. Each movement is likely 
to be very slow and awkward. After the movement has 
been made hundreds of times it requires less attention, 
and the motions are more graceful and accurate. Finally, 
one may make long series of motions without giving them 
any attention whatever. Walking, skating, cycling, 
writing, or playing a piano or violin, eventually become 
quite automatic or mechanical. 

4. REFLEX ACTION AND HABIT (continued) 

Let us understand exactly what automatic motion is. 
The will and the thought are usually involved in auto- 
matic movements, but in quite a different way from that 
which is observed in the beginner who must study the 
details of every movement made. The practiced musi- 
cian reads a measure or phrase of his score and wills to 
execute it as a whole, while the fingers fall into place 
more or less automatically to correspond with the thought 
in the mind of the player. In a similar way, the writer 
thinks words, leaving the making of each word largely to 
the fingers. This is especially true of the shorter and 
more frequently used words. The less familiar and 
longer words require some attention. Writing with a 
typewriter becomes automatic in the same way and to the 
same degree ; so also the use of the telegraph instrument. 

1 Of course the one who finds himself on skates or on a bicycle for the first 
time is likely to make a good many involuntary motions, hut they are extra 
and not necessary, though they may be a usual part of the beginner's exercise. 



56 PHYSIOLOGY 

What is the difference between the first labored efforts 
and the final automatic regularity, speed, grace, and accu- 
racy? Practice has made one movement suggest the 
next, and once the combination of movements is willed 
and the series of movements begun, all of the details of 
the series become reflex and are performed by the cells of 
the spinal cord. 

There is no one property of our systems of greater value 
to us than the reflex action. If it were not for this, we 
should have to give every step our whole attention. In 
fact, one could never learn to do anything gracefullj^, 
accurately, and rapidly. One would always be like an 
awkward, halting beginner. 

Very much like this automatic action of the muscles, 
depending upon reflex action, is a certain property of the 
nervous system which we call habit. 

Webster defines habit as "the involuntary tendency to 
perform certain actions, which is acquired by their fre- 
quent repetition." Further, ''Habit is an internal princi- 
ple which leads us to do easily, naturally, and with grow- 
ing certainty, what we do often." 

A study of this definition of habit must make it clear 
that it cannot be very different from automatic action. 
Both are acquired gradually ; both make it certain that a 
particular series of acts will follow a particular act or 
thought, unless the will power of the brain is used to 
stop it. 

Habit has a wider meaning than automatic action, and 
includes thoughts as well as muscular acts. One may cul- 
tivate a habit of generosity, and a habit of erect carriage 
while walking. One may cultivate habits of industry and 
habits of courtesy; habits of honesty and habits of gen- 
tleness. 



THE NERVOUS SYSTEM 57 

Every important function of the body and mind may be 
diverted from the course for which it was intended by 
nature ; it then becomes as great a curse as it was a bless- 
ing Avhen rightly used. So it is with hahit. One may 
get a habit of stinginess, and a habit of slouchy carriage 
while walking. One may get habits of laziness and habits 
of impoliteness ; habits of dishonesty and habits of cruelty. 

For every good habit there is a corresponding bad one. 
During youth one is always acquiring good habits or bad 
ones. One must do one or the other ; he has no choice in 
the matter. Good habits are a safeguard during all sub- 
sequent life ; bad habits are persistent enemies. It re- 
quires years of constant effort to root them out after they 
are once established ; but it is very easy to keep them out 
in the first place. 



HOW THE ORGANS ARE CONTROLLED — REVIEW 

1. The body is a colony or community of individual cells. Every 
colony or community must be controlled, or the individuals will not 
work in hai'mony, and little will be accomplished. 

2. The Brain is the central controlling powder of the body. Like 
a telegraph station it has operators and conductors (wires). The 
operators are Nerve Cells, and the conductors are Nerve Fibers. 

3. The Brain receives news from various parts of the body, the eyes, 
the ears, and the skin. The Brain sends messages to all parts of the 
body, — to the muscles, the stomach, and the heart. 

4. If one wishes to do something and then does it, w^e call the 
action a Voluntary Action. 

5. If the spinal cord answers a message from the skin, causing 
muscles to move before the brain knows what has happened, we call 
the action a Reflex Action. 

6. If one performs an act many times, it becomes automatic or 
habitual. Automatic and habitual acts are likely to be done without 
thinking. Habits are formed in this way. 



CHAPTER IV. — NARCOTICS— THEIR NATURE, 
THEIR CLASSES, AND THEIR GENERAL 
ACTION UPON THE SYSTEM 

When we come to study the different systems of 
organs, as the digestive system or the circulatory system, 
we shall study not only the way in which the organs act 
when properly cared for, but also the various things which 
injure the organs. Among the things which injure tlie 
body, one of the most important is the use of narcotics. 
Let us devote a few lessons to the study of these sub- 
stances. 

1. NARCOTIC DRINKS 

Narcotic drinks are those that dull the senses, and 
weaken and unsteady the muscles. 

All alcoholic drinks come under this head. They are 
usually called stimulating drinks, because their first effect 
is an apparent stimulation. But they are more often 
taken for the dulling of the sensibilities which follows 
and lasts longer. It is the narcotic property which dulls 
the senses and produces this after-effect. 

It lias recentl}^ been discovered that what has always 
been taken for the stimulating effect of alcoholic drinks, 
is really caused by the narcotic effect upon the self- 
restraint. Alcohol is not a stimulant. 

In the growth of the race from barbarism to civilization 
there has gradually come to be a restraint upon the 

58 



NARCOTICS 



59 



meaner traits, those which cause one to be boisterous, 
uncouth, and passionate. This restraint, being the last 
trait acquired, is the weakest and most easily attacked. 
The first effect of an alcoholic drink is to dull the power 
of restraint, and a person feels excited, which in reality 
means that he cares less what he does ; the next effect is 
to dull the senses. 

No one training for feats of skill requiring strength 
and accuracy is allowed the use of narcotics. 

Alcohol is a clear liquid which looks like water, but 
which burns with a blue flame, giving great heat and 
little light. 





Fig. 20. — The yeast plant, strongly magnified (from Landois and Stirling). 
1, isolated yeast plants; 2, 3, gemmation; 4, formation of endogonidia or 
spores ; 5, budding of spores. 

Alcohol is the result of fermentation. If one adds 
yeast to a dilute solution of sugar, the yeast will change 
the sugar to carbon dioxide and alcohol. 

The yeast which produces alcoholic fermentation is a 
minute plant which grows especially well in sugar water. 
If one were to look at yeast plants through a microscope, 
he would find that they are spherical and live either 
singly or joined together in chains called colonies (Fig. 
20). The principal food of this plant is sugar, which 
the plant breaks up in order to obtain the energy it con- 
tains. This breaking up of the sugar produces carbon 



60 PHYSIOLOGY 

dioxide and alcohol, which the yeast throws off as waste 
products. If we watch the mixture of sugar, yeast, and 
warm water, we can see the bubbles of carbon dioxide 
escaping. The alcohol remains in the mixture. 

In bread making we have a similar process. The 
starch of the flour or the free sugar which is added to 
it is attacked by the yeast and changed into carbon 
dioxide, which, in escaping from the sponge or the 
dough, causes the bread to bubble and become light. 
The alcohol remains in the mixture until it is baked, 
when the heat drives it off. If the bread is not suf- 
ficiently baked to kill the yeast, the growth goes on- and 
the bread becomes sour. 

When water is heated to the boiling point (212° Fah- 
renheit), it rapidly changes to steam or water vapor, 
which collects in little bubbles on the bottom of the kettle 
or other receptacle. The bubbles rise to the top of the 
water, escape into the air, and float away in a little misty 
cloud. When alcohol is heated, a similar change takes 
place, but it does not need to be heated nearly so hot 
before the escape of alcohol vapor begins. When alcohol 
and water are mixed together, as would be the case if the 
alcohol has been made through fermentation of sugar 
water, or fruit juice, the alcohol may be driven off by 
heating the mixture hot enough to vaporize the alcohol 
without vaporizing the water. 

By thus heating the mixture of alcohol and water hot 
enough to boil or vaporize the alcohol, but not hot enough 
to vaporize the water, the alcohol vapor will leave the 
water. If this vapor is caught and conducted through 
pipes which are kept cold by cold water, the alcohol 
vapor will condense again into the liquid form, and can be 
caught as it runs from the end of the pipe or tube. 



NARCOTICS 61 

How similar this process is to sometliing you have 
studied in your geographies ! The sun warms the sur- 
face of the ocean, of lakes, and of other collections of 
water exposed on the earth's surface ; the water is vapor- 
ized, and rising, floats away in the form of fleecy clouds. 
Presently these clouds pass over a range of snow-capped 
mountains, or pass a current of cold air. The vapor is 
condensed and falls as rain upon the surface of the earth. 

In this way the water is separated from the briny solu- 
tion of the sea ; in a similar Avay men separate one liquid 
from another when the two liquids vaporize at a different 
temperature. 

The process of separating one liquid from another by 
vaporizing with heat and condensing the vapor with cold 
is called distillation. 

Men distill water from an impure or briny mixture in 
order to obtain perfectly pure Avater for use in the chemi- 
cal laboratory or for use in manufacturing. Men distill 
alcohol from a mixture of various substances dissolved in 
water in order to get pure alcohol for use in various 
laboratories, for use in manufacturing, or for use by 
druggists in the preparation of medicines. 

Many of the alcoholic drinks are prepared by distilla- 
tion. They contain a much larger proportion of alcohol 
than the original fermenting mixture. Whisky, brandy, 
and rum are all distilled liquors, and contain 40 per cent 
or more of alcohol. 

2. FERMENTATION AND DISTILLATION 

All the alcoholic drinks are first fermented, and many 
of them go no further than this process. Among those 
which are made by simple fermentation are beer, wine, 
and cider. 



62 PHYSIOLOGY 

In the beer making process, corn, or more commonly 
barley, is put into a damp, warm place and allowed to 
stay until it sprouts. We remember that in our study 
of the corn plant we found that, when the seed began to 
grow, the starch of the kernel was changed to sugar. 
As soon as part of the starch has been changed to sugar 
and dissolved out with water, hops and yeast are added, 
and fermentation takes place. In this condition it is 
bottled if it is to be used as beer, but if at this point it is 
put into a still and the alcohol driven off and caught, it 
makes whisky. If to the whisky certain flavors are added 
a drink called gin is made. 

When sugar cane is fermented and distilled, the dis- 
tilled product is called ru7n, and when wine is distilled, 
the product is called hrandy. 

Whisky, gin, rum, and brandy are called ardent spirits, 
and are as much as one half alcohol. 

Pure wine contains from five to sixteen parts of alcohol 
in a hundred, but the wine that is obtained in the market 
often contains as much as one fourth (25 per cent) 
alcohol. 

Beer and cider contain from four to fourteen parts of 
alcohol in a hundred. 

Alcohol is the same wherever it is found, and the main 
difference in the effect of different alcoholic drinks upon 
the system is due to the difference in the amount of alco- 
hol which each contains. Three glasses of some cider 
contain as much alcohol as one glass of strong wine or 
the same glass filled with one quarter whisky and three 
quarters water, and an alcoholic habit can be acquired 
from cider drinking or wine drinking as well as from beer 
or spirit drinking. 

The great transformation which takes place in the juice 



NARCOTICS 63 

of grapes as a result of fermentation is thus strikingly 
summed by Professor Gaule, of the University of Zurich, 
Switzerland : '' Between the sweet juice of the grape which 
does not intoxicate and the intoxicating wine which the 
drinker loves, a foreign element has enteved^ fermentation ; 
that is, the life process of a little fungus — yeast — which 
feeds upon the juice of the grape and rejects the wine. 
That which we drink as wine has no more to do with 
grape juice than, for instance, the arrowroot (starch) of 
the plant has with the carbonic acid of the air on which it 
lives. The one as well as the other is a product of a 
chemical change which is brought about by the life pro- 
cess of an organism, though, to be sure, in quite the oppo- 
site sense, for the green plant cell glorifies that which it 
consumes, in that it forms from dead substances, carbon 
dioxide and water, a great source of power (sugar), while 
the yeast cell does exactly the opposite, consuming sugar 
and robbing it of most of its power, and casting out as 
waste substances carbon dioxide and alcohol." 

FALLACIES CONCERNING BEER 

Beer has been called " liquid bread " from the idea that 
because it is made from grain, as is bread, it is therefore 
nourishing. In Germany this idea has found expression in 
the saying that '' where the brewery is, no bakery is needed." 

A saloon keeper in England once advertised his beer as 
"liquid bread." A member of the British Parliament 
had a chemist examine it. Two per cent was really food. 
Five per cent was alcohol, and the remaining ninety-three 
per cent was water. 

Let us look into this claim a little more closely. Ac- 
cording to standard analyses, lager beer contains: — 



64 PHYSIOLOGY 

89.75 % water, .15 % carbonic acid, 

5.10 % alcohol, 5.00 % malt extract. 

The malt extract, which is the only part that could be 
said to have nutritive value, consists of malt, sugar, dex- 
trin, a very slight quantity of albuminous matter which 
has escaped the processes designed for separating it out, 
and some bitter principles and volatile oils. All that is 
nourishing in this could be purchased in bread for one 
tenth what it costs in beer. 

The healthy grown person requires daily from four hun- 
dred and fifty to five hundred grammes of the kind of food 
that is represented in this extract in the beer. To get 
this amount one would have to drink eight quarts of beer, 
which would contain about nine ounces of alcohol. The 
poisonous effect of this amount of alcohol would very 
quickly show itself. 

Professor Rosenthal of Erlanger says, ''Beer is not a 
food, but a luxury. Let a man drink much beer, enough 
to make the amount of nourishment in it of value, and the 
other influences produced by such a quantity will become 
manifest to such a degree as to cast the factor of nourish- 
ment in the background. If he drinks little beer, the 
food value is not appreciable." 

The claim is also made that the food substances in beer 
are " pre-digested," because they are in soluble form ready 
to be absorbed. Supposing there were enough of this 
"• pre-digested " food in beer to be of sufficient importance 
for consideration, whatever advantages to digestion there 
might be in its being " pre-digested " are offset by the fact 
that beer retards the digestive process. 

To say that substances like beer or alcohol do not need 
to be digested because they are already '' pre-digested " is 



NARCOTICS 65 

only saying that they are in a condition to pass through 
the walls of the alimentary canal into the blood. This is 
no recommendation if it is their nature, when they reach 
the blood, to do harm, as is the case with beer and other 
alcoholic liquors. 

Although certain ''light beers" may contain only a 
small quantity of alcohol, they are by no means harmless 
'' temperance drinks," as is sometimes urged. The London 
Lancet of April 1, 1899, asked, ''Does the consumption of 
more beer really mean the consumption of less spirit ? " 
and answered the question by saying, in substance : Few 
physicians will admit such an opinion. AVe certainly 
know of no instance in which a spirit drinker was saved 
by the drinking of more beer. The remedy, if not worse 
than the disease, is but one shade better. Beer drinkers 
are by no means free from the vice of spirit drinking, and 
are certainly not seldom the victims of the same diseases 
of the kidneys and liver as those which are likely to 
afflict the drinkers of ardent spirits. 

3. THE GENERAL EFFECT OF NARCOTIC DRINKS UPON 

THE systp:m 

Alcoholic drinks seem to be at first stimulating, and 
later to have a dulling effect. 

This stimulation is, however, not real, but only seeming, 
and is caused by the dulling of the power of self-restraint. 

A civilized man restrains himself; he does not allow 
himself to say certain things, or to do certain things ; he 
does not hoot and howl, he does not laugh immoderately 
nor weep at trifles, because he restrains himself. The dull- 
ing effect of a narcotic first acts upon this self-restraint, 
and a person becomes boisterous, loud, and rude. He talks 

hall's phys. — 5 



66 PHYSIOLOGY 

too much, and is not considerate in his treatment of others. 
As this dulling goes on, it affects his senses and other 
mental powers, so that he is not clear in his thoughts, and 
later it affects his muscles, causing him to reel and stagger. 

The thing about wine and cider which is hard for young 
people to understand is, why there is harm in anything 
made from grapes and apples, AYhich are both healthful 
fruits. But since we have seen how quickly sugar can be 
changed to other substances by the yeast plant, it will not 
be so hard to understand. If one puts a few spoonfuls 
of grape jelly or of marlnalade into a pint fruit jar, fills it 
with warm water, and adds a little yeast, he will find in a 
few hours that it is fermenting. The sugar is being 
changed to carbon dioxide and alcohol. In three or four 
days the liquid will have changed into wine or cider, and 
if it is put into a still, alcohol pure enough to burn at the 
end of the tube may be distilled off from the liquid. 

The juice of apples as it is pressed from the fruit is 
harmless and refreshing, but it remains so only for a few 
hours, after which it contains a little alcohol, which in- 
creases day by day, so that cider w^hich at first was harm- 
less comes very soon to Jbe a little harmful, and in a few 
weeks to be intoxicating, as it then contains almost if not 
quite as much alcohol as beer contains. 

Some think that there is no harm in drinking cider and 
beer. Professor Meyer, of the University of Gottenburg, 
says : " Naturally the lighter alcoholic drinks, such as 
cider, beer, and light wines, cultivate a taste for the 
stronger liquors and ardent spirits. Those who make 
statements to conflict with the undoubted facts of statis- 
tics must either be ignorant of these facts, or else they 
attempt to pervert them in order to apologize for their 
own drinking habits." 



NAKCOTICS 67 

Some people think that alcoholic drinks may be indulged 
in moderately. Let us hear what medical men of this 
country and of other countries have to say about mod- 
erate drinking. " Every drunkard was once a moderate 
drinker, and every man who, by his example, leads other 
men to moderate drinking, also leads a part of them to 
immoderate drinking. He starts a stone rolling which it 
is no longer in his power to arrest." ^ 

''After openiiig the floodgate not one man in a thousand 
can stay the progress of a besetting vice, and of all beset- 
ting vices the alcohol habit is the most inevitably progres- 
sive. An unnatural appetite has no natural limits." ^ 

''Experience has proved that recovery from drunken- 
ness is possible only by complete abstinence from alcohol. 
Moderation does not help, for the taking of a small 
quantity of liquor causes an inordinate thirst for 
more." ^ 

" Alcoholic indulgence extinguishes control. How 
many a pathetic story could I tell of even great and 
good men, the intellectual, high minded, and moral, 
who, confident in their power of knowing when to stop, 
have at last helplessly succumbed and been disgraced."^ 

The effect of alcohol upon a grown up person is 
bad enough ; but it is even worse upon a developing 
person. The effect upon children is worse, because the 
body and brain of the child are in the process of growth. 
Even in the years of early manhood, alcohol is very harm- 
ful to the proper development of body and mind. Dr. 



1 Professor G. von Bunge, Professor of Physiological Chemistry, University 
of Basel, Switzerland. 

2 Felix Oswald, M.D. 

3 r/ie Lancet, London, June 8, 1895, p. 1468. 

4 Charles R. Francis, in The Medical Pioneer. 



68 PHYSIOLOGY 

G. H. McMichael says : '' During the years of adoles- 
cence, while the brain is only partially developed, the 
nervous organization is not in the stable condition which 
marks the full vigor of normal, adult manhood. This 
being so, the desire for alcoholic drinks is much more 
easily acquired between the ages of seventeen and 
twenty-five than in later life." 

4. THE GENERAL EFFECT OF NARCOTIC DRINKS, 

ESPECIALLY ALCOHOLIC DRINKS, UPON 

THE Sl^STEM 

I. ALCOHOL A POISON 

Before we can properly study alcohol as a poison, we 
must know what a poison is. A poison is any substance 
which, absorbed into the blood, is capable of injuring the 
body, either by causing damage to the tissues or by 
producing functional disturbances. From this definition 
we see that a poison may disturb the mode of action of 
the tissues or organs without causing permanent damage 
to these structures, or a poison may injure the system by 
changing the structure of the tissues. AUbut's "' System 
of Medicine" says, alcohol ''acts directly on the nerves 
as a functional poison," and Professor Woodhead says : 
" Alcohol exerts an exceedingly deleterious action on 
rapidly growing tissues, interfering with their nutri- 
tion, and preventing the development of their proper 
function. In old age, when the tissues are on the down 
grade and are subject to various degenerations, alcohol in 
most cases merely accelerates the process of decay." 

Professor Pick, of the University of Wurzburg, in Ger- 
many, defines a poison as any substance which, being mixed 
with the blood, causes a disturbance in the functions of 



NARCOTICS 69 

any organ, and adds, "that alcohol is such a substance 
cannot be doubted." He calls the attention of his 
countrymen to the fact that '' the English language 
appropriately calls the disturbance caused by alcoholic 
drinks intoxication^ which by derivation me'diis poisoning,'' 
Professor Forel, of the University of Zurich, Switzer- 
land, says : ''Alcohol, even when diluted, as in wine, beer, 
and cider, is a poison which changes the active tissues of 
the body, causing them to become fatty, either by having 
fat deposited in them or by the changing of the tissues 
themselves to fat. Even in such small amounts as a glass 
of wine or a pint of beer taken with meals, it is injurious 
because it injures the brain by dulling its activity and 
deranging its functions. This has been clearly demon- 
strated by the experiments of numerous investigators.^ 
The most moderate drinking of alcoholic beverages is 
qu-ite useless for anybody, and by means of the example 
produces very great injury to the people in general, 
because many will be led to drink who would not other- 
wise have done so, and of the many who begin as moderate 
drinkers, few will remain moderate drinkers.*" 

II. INFLUENCE OF ALCOHOL UPON THE BODY 

" France presents a splendid illustration of a country 
whose inhabitants made free use of alcoholic drinks, begin- 
ning usually with light wines. And as a result, this great 
country, with its beautiful climate, its fertile soil, and other 
material advantages, equal to the most favored portion of 
the earth, at the present time actually depends upon immi- 
gration to keep up the numbers of its population. The 
leading men of France are seriously studying the ques- 

1 Such investigators as Kraepelin, Smith, Fiirer, Aschaffenburg, and others. 



70 PHYSIOLOGY 

tion, ' How to prevent the depopulation of France ? ' The 
French nation, descended from a race of gigantic Gauls, 
who struck terror to the hearts of their enemies by the 
very magnificence of their presence, has declined to such 
a degree from the stunting influence of alcoholic and simi- 
lar drinks upon their growth, that the average height of 
the people at the present time is actually less than that 
of other civilized nations. The facts witnessed in wine 
growing districts and in wine growing countries certainly 
do not commend the universal use of wine as a remedy for 
intemperance — a use for which it has been suggested." ^ 

According to Dr. Brunon, the population in Brittany is 
being rapidly decreased through the use of alcohol. Alco- 
hol has become a part of the regular table supply of the 
home. Coffee and beer, or some other alcoholic drink, 
form the basis of the dinner ; and if one of these must be 
omitted, it is the coffee. The most distressing feature of 
the case is the serious effect that this use of alcohol has on 
the young. The death rate of young children is very great, 
such as is met with nowhere else.^ 

The Consular Reports of 1895 quote a writer inX^ Havre 
as saying, — 

'' Alcoholism is the great misfortune of the present day, 
and if the evil is not corrected, France will be changed 
into a nation of brutes by this ignoble vice. The peril is 
evident, and it is high time to check it. I know that the 
infamous vice is not peculiar to our country, but I see that 
its ravages are greater here than elsewhere." 

" The workingmen, women, and children of our coun- 
try absorb, in its various forms, a poison which filters 

1 J. H. Kellogg, M.D., Jouimal of Medical Temperance Association, Octo- 
ber, 1897, p. 126. 

2 From the JSformandie Medicale, quoted in Medical and Surgical Reporter, 



NARCOTICS 71 

through their bodies, which, even in small closes, daily re- 
peated, breaks the strength, paralyzes the nervous system, 
destroys the intelligence, and makes the drinker grow 
prematurely old. It makes in a few years, sometimes 
even in a few months, of an individual once robust, active, 
and a valuable member of society, a being abject, degraded, 
and infirm. This poison is alcohol.''^ 

By strict persistence in total abstinence and hygienic 
living the children of drinking parents may overcome the 
tendency to defective conditions of body and mind, to 
which they are especially liable. A weak will with which 
to resist temptation is frequently part of the inheritance 
which children receive from alcoholic parents. But even 
sucli a will may resist the first glass, and in this way gain 
strength for continued resistance of temptation as well as 
uprightness of character in all directions. 



5. OTHER NARCOTICS 
I. TOBACCO 

Cigars, cigarettes, smoking tobacco, chewing tobacco, 
and snuff are all made from the dried leaf of the tobacco 
plant. 

Tobacco contains a sharp-tasting liquid called nicotine, 
which is a quick-acting and deadly poison. Because of 
this poison, the juice of the tobacco is never purposely 
swallowed ; but in chewing, the saliva dissolves the nico- 
tine, and a part of it is absorbed into the system ; while in 
smoking, the nicotine in the smoke and vapor is absorbed 

1 A. Motet, M.D., of Paris, Member of the French Academy of Medicine, in 
ail address before the VI International Congress against the Use of Alcoholic 
Liquors. Report of Proceedings. 



72 PHYSIOLOGY 

by the saliva and the moist membranes of the mouth and 
nose, and taken into the system, where it exerts all of its 
harmful effects, among which is an irritation of all the mem- 
branes with which it conies in contact. After a time, the 
narcotic effect dulls the sense of feeling, so that the irrita- 
tion, while it still exists, is not felt. This poison in the 
system makes one less able to throw off disease, and some 
of the best insurance companies are refusing to insure 
tobacco smokers. 

The cigarette, being a cheap preparation, tempts boys 
to indulge more in this than in any other form of tobacco. 
While tobacco is injurious to every one, it is far more 
harmful to those who are growing. All physicians agree 
in saying that a boy who uses tobacco can never be so 
large or well-developed a man as he could have been with- 
out it. He can never have the strength of body nor the 
vigor of mind that he would have had except for the use 
of tobacco. 

All physicians agree in saying that no one should begin 
the use of tobacco before the age of eighteen or twenty 
years. If a boy waits to that age before beginning its use, 
the chances are his judgment will be sufficiently matured 
to keep him from it. 

II. OPIUM 

There are other narcotics that have a medicinal value, 
that have also the power of creating a desire for the drug, 
which in its increasing use is fatal. Such drugs are 
opium, the dried juice of the white poppy ; morphine, a 
white powder made from opium ; and laudanum, a solu- 
tion of parts of the opium in alcohol. A habit of using 
any of these narcotics is almost impossible to break, and 
its effects are very serious. 



OPIUM 73 

Paregoric is a weak form of opium in alcohol, and 
should be taken only by prescription from a physician. 

Soothing syrups also contain opium, and should not be 
given to children, as they do not cure but simply stupefy 
the child. 

What has been said in the preceding lessons about the 
influence of alcohol upon the will power, applies with 
equal truth to such narcotics as tobacco and opium. The 
enslaving influence of opium is even greater than that of 
tobacco or alcohol. 

The secret of the power of these things over a person 
who has become addicted to them is that they rob the 
person of a part of the will power, and will power is 
the very thing that is required in order to enable the 
victim to break the habit. 

In the chapter on the nervous system, we found that a 
habit is a blessing^ if a good one^ and a curse^ if a bad one^ 
because the habit is made possible only through a change 
in the nervous system. When the habit has once been 
formed, it requires many months, perhaps years, to break 
it. It requires the constant exercise of the will power. 
How is one to fight a habit on equal terms, if through 
the habit he has been robbed of a part of his fighting 
equipment ? 

Young men who are in training for athletic contests 
where strength, alertness, skill, and accuracy are required, 
are positively forbidden by the managers of the teams to 
use tobacco or any other narcotic, and boys and young 
men entering the employ of a great business house or a 
corporation where their success depends upon strength, 
alertness, skill, and accuracy, as well as integrity and 
industry, would surely reach a much higher success if 
they abstained totally from all narcotics. 



74 PHYSIOLOGY 



REVIEW OF NARCOTICS 

1. Narcotics are substances which dull the senses and the sensibili- 
ties. The most common narcotics are the Alcoliolic Drinks, Tobacco, 
and Opium. 

2. Alcoholic drinks are made by Fermenting sugar with yeast. The 
yeast eats the sugar and throws out carbonic acid gas and alcohol as waste 
matter. 

3. Drinks which are prepared by the fermentation of fruit juices 
or of grain sugars are called Fermented Drinks ; examples are, wine, 
cider, and beer. 

4. Drinks which are prepared by the distillation of the fermented 
liquors are called Ardent Spirits; examples are, whisky, brandy, gin, 
and rum. 

5. Alcoholic drinks seem to stimulate at first because they dull the 
brain control and the self-restraint. 

6. Alcoholic drinks dull all of the senses and all of the sensibilities, 
weaken the will power, and create a thirst for more alcohol. 

7. The moderate use of alcohol is very likely to lead to the im- 
moderate use of it. 

8. The immoderate use of alcohol causes disease, degradation, 
misery, and crime. 



SPECIAL PHYSIOLOGY 

Under General Physiology and Hygiene we have 
studied briefly the physiology of a plant ; we have 
studied the cells and tissues of which the organs and 
systems of organs are built up ; we have studied the 
means by which the organs are controlled and made to 
work together harmoniously ; and we have studied some 
of the more important things which harm the body through 
injury to the tissues or through derangement of the func- 
tions. 

We are now prepared to enter upon a detailed study of 
each system of organs of the human body. This part 
of physiology is called Special Human Physiology, 



75 



CHAPTER v.— NUTRITION — HOW THE BODY 
IS NOURISHED 

Th^ term Nutrition is used in physiology to include all 
of the work that tissues and organs do in the Prepai^ation 
of Food for absorption, which includes Mastication^ Swal- 
lowing^ and Digestion^ the Absorption of food and the 
Assimilation of food, under which head one studies how 
food material is built up into the living active tissues of 
the body, as well as the oxidation of food material and 
of tissue material. One may, under the head of Nutri- 
tion, study Foods^ as well as those parts of domestic econ- 
omy which deal with the choice and preparation of food, 

1. WHY WE EAT 

If you have ever watched a locomotive in motion, you 
must have seen the fireman putting fuel into the firebox. 
You know just as well as the fireman does that if he should 
stop putting coal on the fire the engine would stop going. 
He knows something which you do not know, and that is, 
how much coal to put on to make the engine go a given 
distance. 

Many railroad companies and many large factories 
analyze coal from different companies before they buy, in 
order to know which coal will give the most heat and 
motion per ton or per dollar's worth. 

The amount of heat and motion Avhich a fuel produces 
can be exactly measured. The coal which is used in the 
locomotive becomes oxidized and changed into carbon 

76 



NUTRITION 77 

dioxide and water, with smoke and ashes left over. The 
oxidation of the carbon of the coal causes the heat to be 
given off. The heat under the boiler produces from the 
water steam, whose pressure in the cylinder moves the 
piston and turns the wheels. The engine itself is not 
built up by the fuel which it consumes, and it gradually 
wears out. 

We take food into our bodies to supply heat and motion, 
and if the food be tested we can tell exactly how much 
heat and motion it will give. In the experimental station 
at Washington and in many laboratories, men are at work 
finding how much energy can be obtained from different 
foods when prepared in different ways. 

Food Avill give the same amount of heat and motion 
when burned in a furnace as when consumed in the 
body. 

If the government wished to move an army of men 
from one city to another, it could either feed the men on 
nourishing food and give them a long time in which to 
walk there, or it could use the same food in an engine, 
which would carry the men on a train in much less time. In 
this case some extra food must be given the men to keep 
them warm, as the heat which would be enough to do this 
is lost from the engine. Bread is, however, too bulky to 
carry and too expensive to burn, so instead of bread we 
use in a locomotive a fuel like coal, which takes up less 
room and costs less. 

A loaf of bread burned in a furnace and one consumed 
in the body give out exactly the same amount of heat and 
motion. The food which we consume is changed into 
fluid form, and then goes to build up tissues just as it 
does in the plants. 

In selecting coal, the buyer chooses that which gives the 



78 PHYSIOLOGY 

most power for the money, without regard to the looks of 
the coal or the color of the flame. 

In choosing food to supply our bodies with heat and 
motion, what should we think of first ? Should it not be 
the amount of power it contains ? In other words, food 
should ^be chosen to give the most nourishment for the 
least money, provided it can be made to look well enough 
to be appetizing and taste well enough to be palatable. 
Here comes in the work of the cook, who can choose and 
prepare the food, and add the seasoning and the decoration. 

We should think an engineer very wasteful if he used 
more coal than is necessary to make his engine do the 
work he needs. Is it not equally wasteful for us to eat 
more than we need for our work simply because it tastes 
good and we enjoy it ? 

That which is harmful should not be eaten, although we 
may like it. That which is nourishing should often be 
taken, even though we do not like it. If one thinks of 
the good which a wholesome and nourishing food will do 
the body, instead of thinking whether the taste is most 
pleasing to him, he may readily cultivate a real liking 
for a food which might at first seem distasteful. 

2. WHAT WE EAT — FOODS 
I. EGGS AND MILK 

We have decided that food shall be chosen first for the 
energy it contains, and to do that best we must know of 
what different foods are composed. 

Let us look first at the egg^ for in this we have what is 
to the animal world just what the seed is to the plant 
world. If we examine an egg carefully, we find an outside 
shell that corresponds to the shell of a nut. Underneath 



NUTRITION 79 

the shell we find a tough skin like the skin that covers all 
seeds ; inside the skin a white fluid and a yellow fluid 
which are the food, and just under the very thin skin 
of the yellow part or yolk we see a white spot with a 
ring around it, which is the germ or young chick. The 
young chick is surrounded by the food which it will need 
when it wakens to life, just as the young plant is. Both 
the plant germ and the chick germ are sleeping proto- 
plasm. They sleep until the heat wakens them to life. 
The seed needs also moisture to soften the food, but the 
egg is already supplied w^ith Avater enough. 

The yolk of the egg is so balanced that the germ spot is 
always up whichever way the egg is turned. In this Avay 
the germ is kept next to the heat which the mother hen 
supplies from her body when she sits on the eggs. The 
yolk of the egg is proteid and oil, with some mineral 
matter. The oil gives it the yellow color. The white of 
the egg is pure albumen, or proteid with mineral matter 
and water. 

From these materials are built up the bones, muscles, 
blood, nerves, and feathers of the chicken. 

The egg is nature's food for young birds. Is it a good 
food for us ? We need bones, muscles, blood, nerves, and 
hair, and if the egg will build up these tissues in a bird, it 
will also build them up in us. It is, however, such con- 
densed food that it cannot be used alone for the food of 
an adult, and not at all, or at most sparingly, for a child 
under one year old. When the egg is raw, it is easily 
digested, but when cooked, it becomes hardened and is 
more difficult to digest. 

Nature has supplied in milk a food for the young of 
higher animals. This food exactly fills the need of the 
young child, and contains everything that a child requires 



80 PHYSIOLOGY 

for its first year's growth. Let us see what materials milk 
contains. The part that makes it liquid is water, the 
sweetness comes from sugar, the cream which rises to 
the top is oil, and the rest is proteid and mineral matter. 
You can see that milk alone would sustain life for a long 
time. 

II. EXPERIMENTS 

You still have a supply of iodine obtained for the experi- 
ments in plant phj^siology. Some of the iodine has its 
original strength, w^hile some is diluted. 

Get from the druggist or from a physician a few ounces 
of Fehling's Solution (composed of a mixture of copper 
sulphate, or blue vitriol, and potash). 

Get also a few four inch or six inch test tubes. They are 
made of thin annealed glass, and maj^ be heated in a flame 
without danger of breaking. If there are no Bunsen gas 
burners in the school building, a common kerosene lamp 
can be used with good results. 

1. Take a few drops of albumen or white of egg in a 
test tube, dilute it with a spoonful of water, and heat it 
over a flame. It will soon begin to turn white and to 
thicken, or coagulate, as it is called. 

2. Take a spoonful of milk and heat it in a similar way. 
It will not coagulate. 

3. To a spoonful of milk add a few drops of lemon 
juice or. any other acid. The milk will coagulate. 

The small masses which separate out from the milk are 
called coagula, and consist of casein^ the principal proteid 
of the milk. When milk is heated, one may notice a thin, 
wrinkled membrane collecting upon its surface. This 
membrane consists of albumin (milk albumen), which is 
the other proteid of the milk. 



NUTRITION 81 

The yellowish part of the milk which can be drained 
away from the casein coagula is the whey. Whey consists 
of water, milk sugar, and mineral matter, with perhaps 
some cream or fat. Most of the fat stays with the casein 
when it separates out in coagula. 

4. Put into a test tube as much grape sugar (dextrose) 
as will stay on the tip of a penknife blade, add a spoonful 
of water to dissolve it, add an equal amount of Fehling's 
Solution, bring the mixture to a boil over a flame, and 
notice the orange or brick-red, heavy precipitate which 
first clouds the mixture, then settles to the bottom of the 
tube. This is copper oxide, which separates out of Fehl- 
ing's Solution when that is heated with a solution of 
dextrose, or of milk sugar (lactose), or of malt sugar 
(maltose). 

5. Put a spoonful of Avhey into a tube, and add an equal 
amount of Fehling's Solution. Heat it over a flame, and 
note the separation of the copper oxide, again showing the 
presence of dextrose, or lactose, or maltose. In this case 
it was lactose, or milk sugar. So milk contains proteid, 
sugar, and fat. 

3. WHAT WE EAT 
I. CEREALS 

Grains which are used for food are called cereals. They 
belong to the grass family, and form an important part of 
our food. 

Corn, wheat, oats, barley, rye, and rice are cereals, and 
from these we get corn meal, cornstarch, wheat flour, 
graham flour, oatmeal, barley, rye flour, rice flour, and 
various other meals, flours, and prepared " breakfast 
foods." 

hall's phys. — 6 



82 PHYSIOLOGY 

If we look at a grain of each of the cereals, we find they 
all have a skin covering the grain. The oats, barley, and 
rice have a tough, chafflike skin, which is always removed 
before it is put on the market for food. Barley and rice 
are so seldom seen with the skin on that we think of them 
always as white grains. 

Under the skin of the wheat and rye, oats and barley, 
is a brownish or yellowish coat that is very rich in proteid 
and mineral matter, while the inner part of the seed is 
starch containing some proteid and mineral matter. At 
the end of the kernel and on the opposite side from the 
long groove we find the germ, which is of protoplasm and 
very nourishing. 

Most of the proteid part of these small grains, especially 
wheat, is a sticky substance called gluten, and it is this 
gluten which makes many of the wheat breakfast foods 
seem sticky when cooked. In white wheat flour we have 
the starch with some gluten and mineral matter. In 
" whole wheat " or "• entire wheat " Ave get the starch and 
all the gluten and mineral matter from the brown coat, as 
it is not bolted ; and in graham flour we get all the con- 
tents of the grain and the skin as well. There is no 
nourishment in this skin, but it makes the flour coarse, 
and thus excites or stimulates the formation of digestive 
fluids, as well as the movements of the stomach and intes- 
tine. 

It is sometimes said that white bread is not nourishing ; 
that you can see is not the fact, but you can see equally 
well that the whole wheat and graham flour is much more 
nourishing to the whole body, and especially to the bones 
and teeth, as the greater part of the mineral matter lies 
in the brown coat which is bolted out of the white flour. 
Growing boys and girls need much of the bone making 



NUTRITION 83 

material to be found in whole wheat and graham flour, 
in the cereal breakfast foods and in corn meal. 

Great care should be taken in the preparation of cereal 
foods, for unless they are well cooked they are hard to 
digest, and some of the nourishment is lost. Some of 
these cereals are said to need two minutes' or fifteen 
minutes' cooking, but in every case the food is much im- 
proved in wholesomeness by at least thirty to forty minutes' 
cooking. 

II. EXPERIMENTS 

Soak some grains of corn, wheat, oats, rye, barley, and 
rice in warm water for two or three days. 

1. With a penknife and a strong needle dissect off the 
thick, husky, outside shell of a kernel of oats and barley. 

2. Dissect off the thin, transparent skin of corn, of 
wheat, and of rye. Find the germ of each kernel. Make 
some thin slices across each kernel, and draw a figure 
showing the location of the germ, and the food material 
which the parent plant stored for the sleeping young 
plant. 

3. Place a slice from each grain into a few drops of the 
dilute iodine in a watch crystal, and notice the blue color, 
showing both the presence of starch and its location in 
the kernel. Notice that the germ and that part of the 
kernel in its immediate vicinity do not turn blue, and, 
therefore, contain no starch. 

4. Put slices of each grain into strong iodine, and after 
they have been acted upon for several minutes, rinse off 
the iodine. Notice that the starch is turned to a very dark 
blue and the germ and its surrounding food material to a 
brownish yellow. Strong iodine turns proteid matter this 
color. The oil is mixed in with the starch and proteid, 



84 PHYSIOLOGY 

and is not so easily shown by a simple experiment. If a 
kernel of grain be burned, a small amount of ashes remain- 
ing will represent the mineral matter. 

Remember that cereals contain starch, proteid, oil, and 
mineral matter. 

4. WHAT WE EAT (continued) 
I. VEGETABLES 

Ix our study of the cereal foods we found that they 
contain all the kinds of nourishment. They alone can 
sustain life. There is another class of foods which we call 
legumes. These are the beans, peas, and lentils. These 
also are rich in proteid and starch, and have some oil, 
mineral matter, and cellulose, and like the cereals form a 
perfect food, but in such condensed form as to need some- 
thing else to help them through the digestive tract. 

There is still another class of foods which gives nour- 
ishment in a much less condensed form and provides the 
variety which we need to give relish to our food. This 
class includes the vegetables. 

Let us taste a bit of beet, turnip, parsnip, carrot, and 
of onion, and in all of them we shall notice a sweet taste. 
These vegetables we eat for the sugar they contain, and 
for the mineral salts, which we cannot detect by taste. 
They contain also a large amount of cellulose, which has 
no nourishment, but which, by stimulating the digestive 
organs, helps them in their work. If we taste a piece 
of white or sweet potato, we shall notice that it is rough 
to the tongue and has a raw taste. This is due to the 
presence of starch. The sweet potato has some sugar in 
addition to the starch. 

All of these vegetables which contain starch or sugar are 



NUTRITION 8e5 

very nourishing, but cannot be used alone as food, as tliey 
have ahnost no proteid and oil. Because of this lack of 
these substances, many vegetables are prepared with milk 
and butter in the cooking, and are in this way supplied 
with oil and proteid. 

Such vegetables as cabbage, lettuce, celery, spinach, and 
other greens are used largely as a relish, and contain 
almost no nourishment^ They are, however, very impor- 
tant as a relish, and some of them have other uses. Let- 
tuce and celery have a juice that is soothing to the nerves, 
while spinach and other greens contain more iron than do 
other vegetables. 

Besides these vegetables, there are some vegetable prod- 
ucts that are very valuable as food stuffs. Among these 
are potato starch, cornstarch, arrowroot, sago, and tapioca, 
which are almost pure starch. The first is the extracted 
starch of the potato, the second of the corn kernel, while 
arrowroot and tapioca are from the underground stem of 
tropical plants. Sago is from starch deposited in the 
trunk of the sago palm. 

The vegetable products that are pure sugar are beet 
sugar, cane sugar, grape sugar, maple sugar, molasses, 
and syrups. All sugars and syrups, with molasses and 
honey, are very nourishing and for most people very 
wholesome. 

As potatoes contain principally starch, we usually add a 
little butter and milk to them or eat them with meat and 
gravy. Milk and butter are also often added to beans, 
peas, parsnips, carrots, cabbage, celery, and onions. 

Macaroni, which is made from flour and water and con- 
tains as much proteid as wheat supplies, is still largely 
starch, but when cooked with milk, butter, and cheese 
contains all the elements of food. 



86 PHYSIOLOGY 



II. EXPERIMENTS 



1. Make a careful dissection of a soaked bean, and of a 
pea, making a drawing to show the thin skin and the two 
halves of the kernel, which represent the seed leaves. 
Find the tiny stem and rootlet of the germ plant. 

2. Make thin slices of the soaked kernels and treat 
them with dilute and with strong iodine, and note the 
results. 

3. Make thin slices of turnip, parsnip, carrot, and 
onion, and test one kind of vegetable at a time by put- 
ting a slice into a test tube with a spoonful of water and 
of Fehling's Solution. Heat to boiling over a flame, and 
notice that the slice turns a brick-dust red or orange, 
showing the presence of sugar (dextrose). 

4. Test the same vegetables with dilute and strong 
iodine, and notice that there is no starch and no proteid, 
except perhaps, a little proteid just under the skin. 

5. Test slices of white and sweet potato for sugar and 
for starch and proteid. Note results. 

5. WHAT AVE EAT {continued) 
I. FRUIT 

All the foods we have talked about, with the exception 
of milk and eggs, have been vegetable products, and the 
fruits also belong here. Among the many fruits, we find 
some much sweeter than others. These are eaten largely 
for the sugar they contain and their healthful effect upon 
the digestion. Such fruits are apricots, peaches, pears, 
plums, cherries, grapes, and some apples. Bananas are 
rich in sugar, but lack the refreshing juices of the other 
fruits. 



NUTRITION 87 

Oranges, many apples, quinces, and crab apples are 
chiefly valuable for their acid, although they also contain 
sugar. 

The lemon and lime have no sugar, but are very 
important foods because of the acid and salts which they 
contain. 

Fruit is especially needed in the summer weather and 
in warm climates, wdiile fats are needed in cold weather 
and in cold climates. 

II. MEAT 

As yet nothing has been said of animal food, and we 
have already seen that life could be sustained without any 
animal food, for it contains no new material. It does, 
however, contain the most nourishing kind of food in a 
condition easy to use. Meat is composed of proteid matter 
and fat, held together by connective tissue, such as bone, 
gristle, and so forth. We are likely to think that porter- 
house steak at twenty-five cents a pound is more nourish- 
ing than other cuts of meat at six or ten cents per pound. 
If both are broiled, it is true the porterhouse steak will 
yield more nourishment, but the cheaper meats by long 
cooking become equally nourishing, because the cooking 
changes the connective tissue to gelatine, which is proteid 
food. 

Have you not noticed when the water in which a soup 
bone has been cooked becomes cold it looks like jelly? 
That comes from the changed connective tissues of the 
bone, gristle, etc. Let us make some menus that will 
contain a healthful variety and yet give all the elements 
of food at a low price. 



88 



PHYSIOLOGY 



MENU NO. 1 
Breakfast. 



Cereal food. 
Omelet. 



Milk. 



LUXCHEOX. 

Creamed potatoes. 
Brown bread. Apple sauce. 



Potatoes. 



Dinner. 

Beefsteak. 

Grapes. 



Spinach. 



MENU NO. 2 

Breakfast. 

Soft boiled eggs. Bread and butter. 

Cereal coffee. 

Luncheon. 

Made dish of rice and meat. 

Prunes. Bread and butter. 

Dinner. 

Pork and beans. Tomato sauce. 

Potatoes. 

Sliced oranges. 



MENU NO. 3 

Breakfast. 

Luncheon. 

Graham bread. 

Dinner. 

Boiled beef. 

Baked apples with cream. 



Milk toast. 
Cold meat. 

Carrots. 



Cereal coffee. 
Sliced potatoes. 

Potatoes. 



REVIEW OF FOODS 89 



REVIEW OF FOODS 

j . Nature's food for the young of higher animals is milk. 

2. Nature's food for little chickens or other birds before they are 
hatched is e^gg. Eggs and milk contain all that the body needs for 
its growth and development. 

3. Milk and Egg contain Albumen, or Proteid, and Fat, and Water, 
and Mineral Matter. Milk also contains Sugar. 

4. The Grains or Cereals contain Starch, Fats, Proteid or Albumen, 
and Mineral Matter. 

5. Peas and Beans contain starch, oil, mineral matter, and are very 
rich in proteid. People who eat no meat use milk, eggs, and peas or 
beans freely in order to get enough proteid. 

6. Some fruits are full of sugar and are, therefore, very nourishing : 
grapes, peaches, plums, cherries, etc. 

7. Some fruits are acid and are refreshing and wholesome in sum- 
mer : lemons, oranges, apples, etc. 

8. Meats are usually eaten freely though they are not necessary, 
because the vegetable foods with milk, eggs, butter, and cheese make 
a sufficient and perfectly wholesome diet. Meats are rich in proteids, 
fat, and mineral matter. The expensive meats are not more nourish- 
ing than the cheaper cuts. 



6. THE STRUCTURE OR AXATOMY OF THE DIGESTIVE 

SYSTEM 

The Digestive System consists of the Alimentary Canal., 
with certain glands whose ducts or tubes open into the 
canal. The alimentary canal consists of a series of hollow 
or tubular organs through which the food passes during 
the process of digestion and absorption. Beginning with 
the mouth the food passes down the esophagus into the 
stomach. (Make a careful study of Fig. 21 while reading 
this description). After it leaves the stomach it passes 
through the coiled small intestine^ which is subdivided 
into duodenum., jejunum^ and ileum. Passing from the 



90 



PHYSIOLOGY 



SI & Sm.— 



ileum into the large intestine through a small opening 
it comes into the ccecum^ then passes upward, across, and 
downward through the colon into the rectum, (Compare 

Fig. 22 with Fig. 21), 
The glands of the 
digestive system are 
the three pairs of soli- 
vary glands (i\\Q paro- 
tids^ the sublinguals^ 
and the submaxil- 
laries')^ the pancreas^ 
and the liver. The 
liver, however, has 
little to do with di- 
gestion, and much to 
do with assimilation 
and excretion. Let 
us now look carefully 
at each of these or- 
gans of digestion, and 
see how each is made 
and Avhat part of the 
work of digestion 
each performs. The 
moutli cavity is 
formed by the cheeks, 
the lips, the tongue, 
and the palate ; the 
latter has an upper 
part hard and bony, 
which extends back into a softer part from which the 
uvula hangs down. Between the cheeks are the teeth, 
whose office it is to masticate the food and mix it with 




Fig. 21. — A diagram of digestive system. 
Par., SI. & Sm., parotid, sublingual, and 
submaxillary glands; Ph., pharynx; Us., 
esophagus; V.C, vena cava vein receiving 
chyle through thoracic duct (Th.d.) from 
lacteals (Lc.) ; Lv., liver; P., pancreas; 
S., stomach; D., duodenum; C, caecum; 
V.Ap., vermiform appendix. 



NUTRITION 



91 



the saliva. There are two sets of the teeth, the tempo- 
rary set of twenty teeth, which is lost at about six years, 
and the permanent set of thirty-two teeth (Fig. 23). 
There are three parts to be distinguished in a tooth : 
tlie crown or part seen 
in the mouth, the root 
or part which projects 
into tlie gums, and the 
line between which is 
called the neck. 

The teeth are com- ■ 
posed of a hard, shiny, 
outside layer called the 
enamel, which acts as 
a protection to the 
teeth, the middle bony 
part or dentine, and 
the inner soft part 
or pulp, largely com- 
posed of blood vessels 
and nerves (Fig. 24). 

Beginning in the 
middle of the jaw, one 
finds on each side of 
each jaw two cutting 
teeth or incisors^ one 
tearing tooth or canine^ 
two semigrinding teeth 
called bicuspids^ and three grinders or molars. Most of 
the teeth have a single root, but the molars have tAvo and 
sometimes three roots or fangs. The saliva, which mixes 
with the food during the mastication by the teeth, comes 
from three pairs of salivary glands : the parotid gland^ 




Fig. 22. — Picture of the organs of digestion. 
a, duodenum, leading out of the pylorus; 
h, liver; c, esophagus; d, pancreas; e, 
stomach ; /, spleen ; g, i,j, k, m, n, parts of 
large intestine ; h, I, small intestine. [From 
Johownot and Bonton.] 



92 



PHYSIOLOGY 



sitviated in front of the ear ; the submaxillary^ sitnatecl 
nnder the jaw; and the suhlingual^ under each side of the 
tongue. These glands make or secrete the saliva and 
give it out when stimulated by tlie presence of food in the 
mouth, or eA^en by the thought of food. The pharynx is 

supplied with two 
doors which prevent 
the food from getting 
into the wrong pas- 
sages. In order that 
the food may not go 
into the nasal passage 
the uvula and soft 
palate turn back dur- 
ing the process of 
swallowing and cover 
the opening ; and 
that it may not go 
into the air tube, a 
little guard, the epi- 
glottis, protects the 
opening of the air 
passage. This is done 
_ , . , . . very quickly, for dur- 

FiG. 23. — ihe jaws and the teeth : 1, 2, mcisors ; . ^ 

3, cauine; 4, 5, bicuspids; 6, 7, 8, molars ; ing the prOCCSS of 

a, vein; 6, artery; c, nerve ; cZ, vein, artery, g^yallowing OUC can- 
and nerve. [From Johownot and Bonton.] ^ 

not take breath. One 
does occasionally try to breathe and swallow at the same 
time, with the result of getting food into the windpipe, 
.causing violent coughing until it is expelled. The 
esophagus is a long tube which has a soft mucous lining 
and a muscular coat of circular bands. In forcing, the 
food along the esophagus the muscular bands do not con- 




NUTRITION 



93 



tract all at once, but in succession, 
pharynx. The first contracts and makes 
smaller, and thus pushes 
the food on to be con- 
tracted upon by the next 
band. This motion is 
called peristaltic action. 
The same kind of motion 
carries the food along the 
whole extent of the ali- 
mentary canal. 



beginning 



at the 
tlie passage 



7. 



OF THE 
SYSTEM 




ANATOMY 
DIGESTIVE 

(continued) 

The Stomach is a pouch 
which holds about a quart 
or three pints ; the open- 
ing between it and the 
esophagus, being near the 
heart, is called the cardia^ 
and the one from the 
stomach into the intes- 
tines is the pylorus. Both 
of these gateways are 
supplied with circular 
muscles which by con- 
tracting close the open- 
ing. The cardiac end of 
the stomach is the storage part, and the gastric juice 
secreted by this end is somewhat different from the 
gastric juice secreted by the pyloric end, which does the 
work of churning and digesting the proteids (Fig. 25). 



Fig. 24. — Diagram of the structure and 
setting of a normal incisor tooth. 
[Bodecker.] L, cuticle of enamel; 
E, enamel ; D, dentine with canaliculi ; 
/, layer between enamel and dentine ; 
B, border-line between enamel and 
cementum of neck ; S, cementum of 
neck ; Ce, cementum of root ; Z, layer 
between dentine and cementum; P, 
pericementum; A, arteriole of pulp, 
branching into capillaries ; F, vein of 
pulp taking up capillaries ; N, medul- 
lated nerve-fibres of pulp ; Eg, epithe- 
lium of gum; Pe, periosteum; Ca, 
bone tissue of alveolus; Pg, papillary 
layer of gum ; Co, cortical bone of 
alveolus or socket ; M, spaces of bone. 



94 



PHYSIOLOGY 



The stomach has four coats : an outside smooth coat, 
a second muscular coat which enables the stomach to con- 
tract and expand, an inner much-folded coat of mucous 
membrane, and one between this and the muscular coat. 




Fig. 25. — Inside of the stomach, front view, showing the folds (or rugae) of 
the mucous membrane. 

which is called the suh mucosa. In the muscular coat the 
muscles run both lengthwise and crosswise, and by con- 
tracting first one set and then another of these muscular 
coats give the stomach a churning motion. 

The inner mucous coat is thrown up in folds when the 



NUTRITION 



95 



stomach is empty, but these are flattened out when the 
stomach is full. 

The gastric glands are situated in the mucous lining 
and pour out the gastric juice when food enters the 
stomach, or when it is in the habit of 
receiving food (Fig. 26). 

The pancreas is a long spongy organ 
which secretes the pancreatic juice and 
empties it into the duodenum near its 
union with the stomach. The small in- 
testine has, like the stomach, four coats, 
but the inner one, in addition to folds 
similar to those which we noticed in the 
stomach lining, is also pushed up into 
little fingerlike projections called villi ^ 
which very much increase the inner sur- 
face of the intestine. The food gets 
into the hollows between the villi and 
is in this way kept from passing so 
quickly through ; meanwhile the villi can 
absorb the digested material. 

The other intestinal juices are secreted 
by the intestinal glands which lie be- 
tween the bases of the villi, and as the 
food is forced along by the peristaltic 
action of the intestine, it becomes di- 
gested and is absorbed by the villi (study 
Figure 27). 

The large intestine is about five feet in length. There 
is little nourishment left in the food when it reaches the 
large intestine, so that it consists of refuse and water. 
This latter is absorbed as it passes along, and the refuse 
is carried away. 




Fig. 26. — A peptic 
gland, from cardiac 
end of stomach. 
Very much magni- 
fied. A, central or 
chief cells, which 
make pepsin; B, 
border or parietal 
cells, which make 
acid. [From Mil- 
ler's Histology.'] 



96 




Fig. 27. — A very much magnified picture of a slice through the small intes- 
tine. [Benda.] Notice the outer strong coat of connective tissue {a), the 
muscular coat (d lengthwise, and e circular), the submucous coat of con- 
nective tissue (/). The mucous membrane (h) with two very large folds 
(A and B) which run crosswise around the inside of the intestine. (See 
duodenum, Fig. 25.) Notice the fingerlike projections {k) which cover th« 
whole surface of the mucous membrane, and are so fine and delicate that 
the surface of the membrane looks and feels like velvet. Between the 
fingerlike projections or villi there are little glands dipping down into the 
mucous membrane. These intestinal glands are similar to the stomach 
glands except that they have no border cells. (See Fig. 26.) 



8. REVIEW OF ANATOMY OF DIGESTIVE SYSTEM 



1. Name the parts of the alimentary canal, beginning 
with the mouth. 

2. Name the glands which form a part of the digest- 
ive system. 



NUTRITION 97 

3. Draw a diagram of the digestive system. 

4. How many teeth have you? How many, if any, 
belong to the temporary set ? How many teeth will be 
required to complete your permanent set, and when ought 
they to appear ? 

5. What provision is made to guide the food on its 
passage through the pharynx ? 

6. How can one swallow water when the head is lower 
than the stomach ? 

7. How many kinds of tissue in the wall of the 
stomach ? What is the work of each ? 

8. What is the advantage of the stomach having a 
lining larger than the outside wall, thus causing the 
lining to be thrown into folds ? 

9. What is the advantage of the crosswise folds of the 
mucous membrane lining the small intestine ? 

10. What are the villi? What are the intestinal glands? 

11. Of what use is the vermiform appendix ? How 
did man come to have such an organ ? How large is the 
rabbit's vermiform appendix ? Is this organ useful to the 
rabbit? Could man live without it? 

9. DTGESTIOX BY SALIVA 

We called j)lant digestion the process of changing food 
from a form in which it cannot be used to a form in which 
it can be used, and the same definition will do for animal 
digestion. 

Plant digestion is, however, carried on outside of the 
plant body, while animal digestion goes on within the 
animal body. The process of animal digestion is so 
thoroughly understood that it can be imitated outside of 
the body, and the process watched. 
hall's phys. — 7 



98 PHYSIOLOGY 

We found that plants cannot use starch until it has been 
changed b)" a ferment. The same is true for animals ; 
and as the process goes on within the body, the mouth is 
supplied with a juice called saliva, which produces this 
change. Starch can be acted upon by the saliva much 
more readily after it is cooked, so that all cereal foods, 
potatoes, and other starchy vegetables, are always cooked 
before being eaten. 

When the food has been prepared, it is taken into the 
mouth and masticated. This process of mastication has 
two purposes : first, to grind it into small particles that 
can be reached by the saliva ; and second, to moisten it 
thorouglily, so that it may be more easily swallowed, and 
so that it will have enough of the saliva to make the 
change. 

It is interesting to watch the process of digestion, and 
to find out just what the change is. Suppose we put into a 
glass tube a little cooked starch, some saliva, a little water, 
and then, after shaking it up, hold it in the warm hand 
for a few minutes. Now, if we put a few drops of iodine 
in the tube, we shall find no blue color, which proves there 
is no starch, but a purple color, which iodine always shows 
in the presence of dextrine, or half digested starch. We 
could go on and show that there is actually sugar present, 
after five minutes of warmth upon the saliva and starch. 
Saliva, then, is a juice whose work is to change starch to 
sugar. 

EXPERIMEI^TS 

1. Prepare starch paste by rubbing starch in water to a 
thin creamy consistency, and boiling until it is clear. 

2. Put into a test tube one fourth teaspoonful of starch 
paste, a little saliva, and an equal amount of water ; shake 



NUTRITION 99 

up the mixture, and hold it in the hand for a few minutes 
to keep it warm. Add iodine, and instead of the blue 
color of the starch, we get a reddish blue color, showing 
that the starch has been changed (to dextrine). 

3. Mix in a test tube, as before, starch paste, saliva, and 
water. Keep warm five minutes. Add an equal volume 
of Fehling's Solution, and heat to boiling. The precipita- 
tion of copper proves that sugar is present (maltose). 

4. Try these experiments with raw starch, and show 
that saliva digests cooked starch much more readily than 
it digests raw starch. 

10. DIGESTION BY THE GASTRIC JUICE 

We found the saliva of the mouth to act upon the 
starchy foods, changing them to sugar. But as saliva 
has no effect upon proteid foods, nature has supplied 
another juice in the stomach to do this work. 

The food, when it is swallowed, takes down into the 
stomach a quantity of saliva which carries on the starch 
digestion. The gastric juice of the stomach does not be- 
gin to flow until after the stomach is stimulated by the 
presence of food ; and, as it collects slowly, it gives the 
saliva time to go on with its work on the starchy foods. 

If we test the saliva, we find it alkaline, that is, like 
soda ; but if we test gastric juice, we find it acid. You 
know when we put sour milk and soda together, one coun- 
teracts the other. This is true of any alkali and acid. 
After enough of the acid gastric juice has collected to 
neutralize the alkaline saliva, the latter can no longer do 
any work. Then the gastric juice begins its work upon 
the proteids. 

During the half or three quarters of an hour in which 
the saliva can work before the gastric juice has made the 



100 PHYSIOLOGY 

stomach too acid, only a small portion of the starchy foods 
has been digested ; the rest passes on into the intestines. 

If the food has been well cooked and thoroughly masti- 
cated, so that the gastric juice can get at every particle, 
the work goes on faster, and with greater ease. 

When we eat sugar, we are relieving the saliva of its 
work by eating food already changed ; and when we eat 
peptonized foods, digested proteid food, or peptone, we are 
relieving the gastric juice of its labor. 

The gastric juice is secreted by the gastric glands (Fig. 
26). These are in the mucous membrane of the stomach. 
Those at the cardiac end of the stomach differ from those 
in the pyloric end in having border cells which secrete 
acid. The gastric juice contains both acid and pepsin. 

EXPERIMENTS 

Get a pig's stomach from the stockyards, or from the 
village slaughterhouse. The stomach of a pig is very 
similar in size and structure to that of a man. Cut it 
open, rinse it off, and make a careful study of the coats, 
and of the mucous membrane. Draw figures, and make 
a full description in your notebook. 

2. With an old table knife or a strong spoon scrape 
the mucous membrane of the stomach, saving the slimy 
scrapings in a pint jar. Add water enough nearly to 
fill the jar, stir or shake vigorously for several minutes, 
add the juice of a lemon to take the place of the acid which 
the gastric glands of the stomach usually secrete. Label 
this : Gastric Secretion, 

3. Buy five cents worth of pepsin from the druggist, 
put it into a pint jar, add the juice of a lemon, and fill the 
jar with water ; shake thoroughly, and label : Artificial 
Grastric Juice, 



NUTRITION 101 

4. Cut or tear off some fine stringlike shreds from a 
piece of raw steak. Put two or three of these into a 
test tube with the artificial gastric juice and keep warm 
for fifteen minutes, noting very carefully all changes. 
Repeat with gastric secretion. 

5. Digest very soft-boiled egg with the two different 
preparations of gastric juice. 

6. Try starch paste and a piece of fat to see if gastric 
juice will digest either. 

11. DIGESTION BY THE PANCREATIC JUICE 

Perhaps you have wondered what became of all the 
starch which the saliva did not digest, and when you 
know that gastric juice digests only a part of the pro- 
teid, and that as yet there has been no effect upon the 
fats, you will see clearly the need for another digestive 
fluid. 

When the food leaves the stomach it consists of the still 
undigested starch, the still undigested proteid, the fats, 
such sugar as we may have eaten, mineral matter, and 
water, besides the dextrine and sugar and peptone which 
have been formed by the saliva and the gastric juice. 
These all mixed together make a grayish, soupy mixture, 
which we call chyme. The chyme leaves the stomach and 
enters the duodenum, the upmost section of the intestine. 
Just at the entrance of the intestine is a tube from which 
the pancreatic juice enters the duodenum, and this juice, 
with the help of the intestinal juice and the bile, con- 
tinues the process of digestion. 

The pancreatic juice has three kinds of ferments, each 
of which has its own particular work. One ferment acts 
upon starch, changing it to sugar ; one acts upon proteid. 



102 PHYSIOLOGY 

changing it to peptone ; and one changes fat into an emul- 
sion, or into soap, which may readily be absorbed from 
the intestine. 

The intestinal juice is secreted by the little intestinal 
glands that are located in the mucous membrane of the 
small intestine, between the bases of the villi. This juice 
contains one ferment which has the power of changing 
such sugars as maltose, lactose, and cane sugar to grape 
sugar, or dextrose. 

The bile is secreted hj the liver, and assists the pan- 
creatic juice in making an emulsion of the fats and oils. 
The bile contains no ferment. The mucus which it 
contains in abundance lubricates the wall of the intes- 
tine, and so helps the food to slide along through the 
narrow canal. 

The combined effect of these digestive juices is quickly 
noticed on the still undigested food, which is soon in a 
condition to be used in the body as nourishment. In 
other words, the food is now digested. 

EXPERIMENTS 

1. Buy from the druggist five cents' worth of Pan- 
creatin ; put it into a pint jar ; add one quarter tea- 
spoonful of baking soda (bicarbonate of soda). ; nearly 
fill the jar with water and shake vigorously. Label : 
Artificial Pancreatic Juice, 

2. Put into a test tube a few shreds of raw steak or 
a bit of soft-boiled egg,, add a half tube of the pancreatic 
juice, and see if it will digest either of these in fifteen 
to thirty minutes. 

3. Put into a test tube a little starch paste, add half 
a tube of pancreatic juice, shake thoroughly, and keep 



NUTRITION 103 

warm fifteen minutes, (a) Take out half of the mixture 
and test with iodine to see if the starch has been partly or 
wholly changed to dextrine. (6) Take the other half of 
the mixture ; add an equal volume of Fehling's Solution ; 
shake to mix ; heat to a boiling temperature and note if 
any of the starch has been changed to sugar (maltose). 

4. Add to a spoonful of olive oil an equal volume of 
Artificial Pancreatic Juice ; shake vigorously two min- 
utes ; note that the oil is changed to a white, milky 
liquid, an emulsion containing some soap. 

Note that some preparations of pancreatin will digest 
proteid and fat ; some will digest starch and fat ; while 
a perfect preparation digests proteid, fat^ and starch. 

12. REVIEW OF THE AVHOLE PROCESS OF DIGESTION 

1. How many digestive juices are there? Where are 
they made or secreted ? In what part of the alimentary 
canal do they do their part of the digestion ? 

2. How many different kinds of food do we eat ? 
Where is each kind digested ? 

3. What is chyme, and of what does it consist ? 

4. How many ferments are at work in the small intes- 
tine ? What is the work of each ferment ? Into what 
final form is starch changed ? Proteid ? Fat ? Cane 
sugar and milk sugar ? 

5. Why do the contents of the small intestine look like 
milk? 

6. What is the test for starch ? For dextrine ? 

7. What is the test for sugar (dextrose, maltose, lac- 
tose) ? What is the reddish substance which separates 
out in the test ? 

8. What is the name of the ferment of the stomach ? 



104 PHYSIOLOGY 

13. THE HYGIENE OF DIGESTION 

Now that we know the elements of food, and what 
value each has in the building up of the tissues, we are 
ready to decide the best method of preparing foods, the 
best time for eating them, and some other points regard- 
ing food and health. 

In tasting a raw potato or raw rice, we noticed the 
granular feeling of the starch and the unpleasant taste. 
If Ave were to try to digest raw starch in a little saliva 
we should find it still undigested after fifteen or twenty 
minutes, while the cooked starch and saliva show dex- 
trine after one minute. The cooking breaks up the starch 
grains and allows the saliva and pancreatic juice to reach 
the starch itself and digest it. 

Therefore, all starchy foods should he thoroughly cooked. 
It does not follow that all other kinds of food should be 
much cooked. For example, raw Qgg digests very 
quickly, while eg^ that has been cooked becomes hard 
and so compact that the gastric and pancreatic juices 
cannot readily penetrate them to digest them. 

Meat ivhich contains much connective tissue must be cooked 
for a long time at a temperature just below boiling^ that the 
connective tissue may be rendered in part digestible ; but 
as a rule, lean meat should be cooked only enough to make 
it palatable. 

There is much talk about the use of meat, and per- 
haps it will be well to say that the people who have done 
the most toward the advancement of civilization have 
been the meat and vegetable eating people and not the 
vegetarians. Although the proteids can be obtained from 
vegetables, there seems to be something else which meat 
alone can give. The fault then is not in eating meat at 



NUTRITION 105 

all, but in eating it too often and in too great quantities. 
One needs more meat in winter than in summer. Eng- 
lish and American people eat too much meat. A proper 
amount of meat makes one active, ^yllile too much makes 
one nervous. People engaged in severe bodily exercise 
can eat much more meat without affecting the nerves 
than can be eaten by students or people engaged in less 
active labor. 

We have seen that starch is an important part of our diet 
and that before we can use it in building up tissue it must 
become sugar. The question naturally follows, why do 
people often say we should not eat sugar nor candy ? Per- 
haps it wdll help us to find out if we remember how many 
of the foods we eat contain starch, which will, of course, 
make sugar ; and if we also remember that sugar is not 
a muscle making, but a heat making food. Sugar and 
candy are nourishing, but if we eat much of them we add 
too much sugar to our diet and make our stomachs liable 
to fermentation. 

Then again, such things would do little if any harm to 
the average person if eaten at the end of a meal, and 
thus taken at a proper eating time. But they are seldom 
taken then, and one of the most injurious things we can 
do is to eat at irregular hours. Why ? Because if we 
are regular in our meal times, the digestive juices become 
regular in the time that they appear in the stomach and 
intestine, and at the usual time for eating they will flow 
freely to do their work. 

If between the meals we take any kind of food, it stim- 
ulates the juices to flow, and then when we need them for 
the regular meal, which is heavier and needs more of 
the juices, they do not flow readily, and the food is not 
well digested. 



106 PHYSIOLOGY 

14. THE HYGIENE OF DIGESTION (continued) 

Having now properly chosen our food and cooked it in 
the best manner, we are ready to decide when it should be 
eaten. Certain people tell us to eat no breakfast, others 
to eat no lunch and still others to eat nothing just before 
sleeping; but all of these things do not touch upon the 
fundamental rule of eating, which is : Uat only so much as 
is needed for nourishmejit^ and eat only at regular hours. 

One of the most frequent causes of overeating is the 
practice of serving too many things at one meal. In 
order to eat a little of each thing presented, more is eaten 
than otherwise would be. This is only one of the draw- 
backs of the practice of serving a great variety at one 
meal. When so many things are served at one meal the 
possible number of things is much sooner used up, and one 
becomes tired of his food, or, as we say, he loses his 
appetite. There is also the added expense in money, time, 
and labor entailed by the addition of unnecessary things. 

Meat is one of the most common articles of diet and we 
have found that it is rich in proteid.. It has been found 
that the nations which use meat are the best thinkers and 
the most progressive people. It has also been learned 
that the people who eat the most meat, the English and 
Americans, are most subject to such diseases as gout, 
neuralgia, and rheumatism. Meat gives no food material 
which cannot be obtained from vegetables, and yet the 
eating of meat seems to give an activity and agility that 
vegetable food does not impart. When meat is eaten in 
large quantities this activity increases until the person 
becomes nervous, restless, and irritable. 

Those who are doing heavy manual labor can eat much 
more meat without receiving harm than can be eaten 



NUTRITION 107 

by less active people. Those who have rheumatic tenden- 
cies should avoid the use of lean meat except in small 
quantities. 

Rich pies, cakes, and puddings you Avill perhaps think 
are useful because they contain sugar, eggs, milk, fat, and 
flour, all of which are nourishing, but unfortunately they 
are so put together as to make them very hard to digest, 
and this makes the time required for digestion longer. 

The main thought in the hygiene of digestion is : Eat 
those things wJiieh are for our bodily good^ although they may 
not he the most pleasing to the taste ; and avoid those things 
which do us harm^ although they are most to our liking. Eat 

TO LIVE, not LIVE TO EAT. 

15. THE HYGIENE OF DIGESTION — AYATER 

In the little corn plant that grew from the seed because 
of the warmth and moisture it had, we found nine parts 
out of ten to be water. In all plants, from the least to 
the greatest, we find a large quantity of water. 

Water is nature's drink, intended for all life. It exists 
in the greatest abundance, and all living things are able 
to procure it. Rivers, lakes, and springs are nature's 
reservoirs for storing pure water. Wells and cisterns are 
man's reservoirs. 

The purest water is that taken from nature's reservoirs 
where they are not near large cities. When the city refuse 
empties into a body of water it leaves many impurities 
and germs of disease. The water must then be taken 
from far beyond the reach of the impurity or it must be 
boiled to kill the germs. Rain water is the purest form 
of water aside from those just mentioned, provided it has 
not become impure after falling. 



108 PHYSIOLOGY 

The artesian well is the most artificial plan of procuring 
water, and water from such wells is often heavily charged 
Avith mineral salts that are not the best for our use. The 
system is unable to take up and use lime and magnesium 
salts in this form. They therefore tend to clog the 
system, causing a tendency to constipation, or if absorbed 
entail very hard work upon the kidneys to throw them 
out of the system. This water is more healthful if 
boiled ; or better yet if distilled. 

Sugar and salt must have water to dissolve and dilute 
them before they can be absorbed by the body, hence the 
desire for drink after eating them. 

All processes of digestion require water to complete 
them. It is, however, not a good practice to wash food 
down with water. Let the saliva moisten the food, and 
let the water be taken, a little at a time, when the mouth 
is empty. 

It is beneficial to take water with the meals and after the 
meals, but it is not so well to drink it just before the meal. 
If ice water is used it should not be taken by the half 
glass but should be sipped^ that it may be warmed before 
reaching the stomach. 

After what has been said of the harmfulness of the 
lime and magnesium minerals in the water, the question 
would naturally follow, why then do we use mineral water? 
These mineral waters which are used as beverages contain 
other minerals than lime and magnesium, and have a 
special medicinal value. Effervescent mineral waters con- 
tain carbon dioxide under pressure. When the pressure 
is removed the gas begins to expand and escape, causing 
the bubbling. The salts of most mineral waters stimu- 
late the excretory organs, and are usually taken for this 
purpose. 



NUTRITION 109 

16. THE HYGIENE OF DIGESTION— DRINKS 
I. REFRESHING DRINKS 

Under this heading we may mention first lemonade and 
other fruit acid drinks^ which are so pleasing to the taste in 
the summer, and really aid in the digestion if taken at the 
right time. The gastric juice of the stomach is acid, and 
will flow freely upon the entrance of food into the stomach. 
But if just before the food is taken we introduce an acid 
into the stomach, the gastric juice will not flow so freely, 
and the food is hindered in its digestion. If the fruit 
acid comes in during the latter part of the meal, after the 
gastric juice has already flowed, it assists in the digestion. 
Fruit acid drinks are then better not taken just before 
or during the early part of the meal. 

Fruit Juices^ such as apple juice or grape juice or rasp- 
berry juice, may be extracted, mixed with a little sugar, 
boiled to kill all germs, and then bottled to prevent 
fermentation. These with the addition of a little water 
also make refreshing drinks. 

Fruit Sirups are fruit juices cooked with enough sugar 
to keep them from fermenting without sealing. These 
must be used with a great deal of water, in order to make 
refreshing drinks. They are more often used as flavor- 
ings for other drinks. 

Soda water^ without flavoring, is simply water and car- 
bon dioxide, and derives its name from the soda which 
was originally used in making the carbon dioxide. In 
this form it may be classed with refreshing drinks ; when 
ice cream, milk, or eggs are added, it should rather be 
classed with the next group. Soda water is usually fla- 
vored with a fruit syrup. 



110 PHYSIOLOGY 



II. NOURISHING DRINKS 



Nourishing drinks^ including milk, cocoa, chocolate, and 
the cereal drinks, such as '^ postum cereal " and '' grano," 
possess a food value in themselves, and when they are 
served with cream and sugar become still more nourishing. 

All of these drinks are best taken with the meals, or 
when food is required, as they demand the work of all the 
digestive juices to digest them. 

III. STIMULATING DRINKS 

The stimulating drinks^ which have no other important 
properties, are coffee and tea. 

Tea contains tannin, which gives the dark color to the 
tea, and hinders the digestion. Neither tea nor coffee pos- 
sesses any nourishing properties, except for the sugar and 
cream that are taken with them. 

17. THE HYGIENE OF DIGESTION — ALCOHOLIC DRINKS 
I. IS ALCOHOL A FOOD? 

Experiments have recently been made by Professor 
Atwater, of the government Department of Agriculture, 
in which new proof of the oxidation of alcohol in the 
body was collected. This has opened again the old ques- 
tion as to whether, because of its oxidation in the body, 
alcohol may be classified as a food. 

We know that foods yield their energy by oxidation, 
either after having been built up into living protoplasm 
or after having been absorbed by the living protoplasm 
and taken into the cells, though the food is not necessarily 



NUTRITION 111 

built up into living protoplasm before the oxidation can 
take place. 

When it was found out, a good many years ago, that 
alcohol is nearly all oxidized in the body, the question was 
at once asked, " Is not alcohol then a food? " 

Investigations were made, and the question was debated 
with the result that alcohol continued to be classified with 
the poisons, and not with the foods. 

The question has been opened several times during the 
last fifty years, but always with the same result. Sci- 
entific men, generally, continue to classify alcohol as a 
poison, and not as a food. 

Morphine is oxidized in the body, and yields its energy 
to the body, yet every one recognizes morphine as a dan- 
gerous poison, though it is often given by physicians with 
benefit in cases of illness. 

So we see that a substance cannot safely be used as a 
food simply because it is oxidized in the body. 

A food is a substance whose nature it is, luhen absorbed 
into the bloody to nourish the body without injuring it. 

When we say that beef is a food, everybody under- 
stands that we mean beef that has been cared for in the 
usual way. If lean meat is exposed to a warm atmos- 
phere for a number of days, a change takes place, caused 
by the growth, within the meat, of millions of bacteria. 
The bacteria themselves would not hurt one if they were 
killed by cooking, but some of the waste matter (pto- 
maines) thrown out by the bacteria would not be made 
harmless by cooking, and might seriously poison any one 
eating the meat. This process of decomposition of meat is 
a fermentation, or putrefaction, and the bacteria are called 
organized or living ferments. 

In a similar way sugar, in a dilute solution in water, if 



112 PHYSIOLOGY 

exposed to a warm atmosphere, will undergo a fermenta- 
tion, caused by the growth, within the solution, of millions 
of yeast plants, which are organized or living ferments. 
The yeast plants themselves would not hurt one, but 
some of the waste matter thrown out by the plant would 
not be made harmless by heating, and if kept from pass- 
ing off by evaporation might seriously poison any one 
drinking the solution. 

It is the nature of meat and sugar, when absorbed into 
the blood, to nourish the body without injuring it ; but if 
ptomaines are formed in the meat, or if alcohol is formed 
in the sugar solution, the previously wholesome foods be- 
come poisonous, owing to the presence of the ptomaines 
or alcohol. 

When we use the word poison, we are likely to think 
of a substance, such as strychnine or arsenic, that causes 
or may cause death in a very short time. But there are 
many poisons that work very slowly, sometimes requiring 
many years to cause death or a serious disabling of the 
system. Painters are sometimes affected with lead poison- 
ing^ due to small quantities of lead absorbed day by day 
for years. If a man were to take a considerable quantity 
of the poison at once, it might cause death in a few hours 
or days. Arsenic may be taken in very small doses day 
after day for many years without causing death, but it is 
no less a poison because it does its damage slowly. 

When alcohol is taken in small quantities, it is oxidized 
in the system, and gives up its heat energy to the body. 
This heat will be given off to the body, just the same as 
heat caused by the oxidation of sugar or bread. But 
the condition of the body, after it has oxidized alcohol, 
is quite different from its condition after it has oxidized 
sugar or bread. 



NUTRITION 113 

Benzine is very easily oxidized. If it were poured upon 
the fire of a locomotive, it would make a furious blaze, 
which would make the water in the boiler heat rapidly, 
and that, in turn, make the wheels turn more rapidly. 
But the benzine would burn so rapidly as almost to make 
an explosion, and a very large part of the heat caused by 
the oxidation would be lost. The locomotive needs a 
slow-burning fuel, whose heat can all be utilized. So the 
body needs such slow-oxidizing substances as sugar, bread, 
starch, and fat, rather than such a rapidly burning sub- 
stance as alcohol. The energy of the alcohol is rapidly 
expended, because the alcohol causes the blood to come to 
the surface of the body, and the blood cools so rapidly 
that more heat energy is lost from the body than that 
contained in the alcohol, thus leaving the temperature of 
the body lower than it was before the alcohol was taken. 

Let us now listen to some of the leading medical men 
as to whether alcohol may be considered a food. 

"Although the relation, just alluded to, between the 
burning of alcohol and the burning of the nutritious sub- 
stances in the animal organism, has not been fully ex- 
plained physiologically, this much is true, that alcohol, 
taken however moderately, is not to be classed among the 
nutritious substances." ^ 

Dr. McConachie, of Baltimore, says : '' Alcohol exerts 
a pernicious influence on the development and function of 
the muscular and nervous systems, the special senses and 
mental activity of those who use it. This is not the role 
played by a true food." 

Dr. A. Forel^ says: ''Alcohol, or ethyl-alcohol, is a 

1 Adolph Fick, Late Professor of Physiology, University of Wurzburg^ 
Germany. 

2 Professor of Nervous Diseases in Zurich, Switzerland. 

hall's phys. — 8 



114 PHYSIOLOGY 

poisonous matter, both for the human and animal organ- 
ism ; its venomousness increases with the amount and 
frequency of the doses. But even when partaken of in 
the most temperate way, it plainly interferes with the 
functions of the various organs ; it cannot be regarded as 
being either nourishing or strengthening ; and therefore 
it is of no use whatever in a normal diet, and cannot be 
counted as a factor of the same." 

''A physicist could experiment with gunpowder and 
prove that it is easily oxidized and gives rise to a large 
amount of heat and energy. From this it might be 
argued that gunpowder is a most useful kind of fuel for 
cooking-stoves. Such a conclusion would be hardly less 
logical than the conclusions that have been drawn from 
these experiments with alcohol, and which regard it as a 
useful food for the body. 

" Gunpowder is a more unsafe fuel because of its sec- 
ondary effects, and in the same way the food value of 
alcohol cannot be determined by its power of being oxi- 
dized, but must include the consideration of its secondary 
effects as well."^ 

" In order to be a food it is not sufficient that a sub- 
stance be decomposed (or oxidized) in the tissues. Under 
these conditions many harmful substances would be con- 
sidered foods. Ether is decomposed in part, chloroform 
is partially destroyed. But do we consider these sub- 
stances foods ? Certainly not. Other things than oxida- 
tion are necessary to nutrition. It is necessary that 
the decomposition be made in a way that will not injure 
the vitality of the cells. A part of the alcohol that is 
destroyed on the body undergoes this decomposition in a 
way that is injurious. Observe that whereas true foods, 

1 Professor H. W. Conn, of Wesleyan University. 



NUTRITION 115 

such as sugar and fat, are destroyed slowly, easily, without 
provoking too lively a combustion, alcohol is burnt too 
rapidly, provoking a veritable explosion. Suppose that a 
locomotive has to run a certain number of kilometers ; in 
order to do this it must be given food. This is the coal, 
which it burns slowly and methodically. If in the place 
of coal we throw naphtha on the fire, the combustion of 
this may furnish as much heat as the coal, but it is burnt 
instantaneously, in the form of an explosion. The heat 
thus produced is not utilized in the machine. What 
naphtha is for the locomotive, alcohol is to our bodies ; it 
is an explosive but not a food." ^ 

When put to a practical test on a large scale, as when 
given to soldiers in severe army work, alcohol fails as a 
food most conspicuously. '' It has been shown over and 
over again that those who endure the greatest fatigue and 
exposure are the men who do not drink." ^ 



II. THE EFFECTS OF ALCOHOL UPON DIGESTION 

Professor Kochlakoff, of St. Petersburg, has experi- 
mented on five healthy persons, aged from twenty to 
twenty-four years, with reference to the effects of alcohol 
upon digestion. Ten minutes before each meal, each 
person was given three ounces of alcoholic liquor, con- 
taining from five to fifty per cent of alcohol, which is 
about the proportion found in ordinary liquors. The 
following results were obtained : — 

" Under the influence of alcohol, the acidity of the gas- 
tric juice and the quantity of hydrochloric acid, as well 

1 Doctor Bienfait, of Liege. 

2 William B. Rochester, Brigadier General, U.S.A. (Retired) =' 



116 



PHYSIOLOGY 



as the digestive power of the gastric juice, was dimin- 
ished. This enfeebling of the digestion is especially pro- 
nounced in persons unaccustomed to the use of alcohol." 

Professor Chittenden and his associates of Yale Uni- 
versity have made extensive experiments upon dogs, and 
have found that, though the presence of alcohol or an 
alcoholic beverage in the stomach causes a greater amount 
of gastric juice to be secreted, still the presence of alcohol 
in the stomach retarded digestion. 

The results which Professor Chittenden gives as 
'' strictly comparable," because "they were carried out 
in succession on the same day," are as follows : — 



Numbei 


of Experiment. 


x^o lb. meat with water. 


xVlb. meat with dihite alcohol. 


XVII 


a 9:15 A.M. 


Digested in 3 hours. 




XVII 


^ 3 : 00 P.M. 




Digested in 3 : 15 hours. 


XVIII 


a 8:30 a.m. 


Digested in 2 : 30 hours. 




XVIII 


/? 2 : 10 P.M. 




Digested in 3 : 00 hours. 


XIX 


a 9:00 a.m. 


Digested in 2 : 30 hours. 




XIX 


^ 2 : 30 P.M. 




Digested in 3 : 00 hours. 


XX 


a 9 : 15 a.m. 




Digested in 2:45 hours. 


XX 


^2:30 P.M. 


Digested in 2 : 15 hours. 




VI 


a 9:15 A.M. 




Digested in 3 : 45 hours. 


VI 


^ 1 : 00 P.M. 


Digested in 3 :15 hours. 




A 


rerage . 


2:42 hours. 


3 : 09 hours. 



From this table of results that may be compared, we 
see that with alcohol present in the stomach the digestion 
was retarded twenty-seven minutes in the average result.^ 

Nothing could be further removed from the truth than 

1 American Journal of Physiology, Vol. I, 202-203. 



NUTRITION 117 

the popular notion that alcohol, at least in the form of 
certain wines, is helpful to digestion. Roberts showed, 
years ago, that alcohol, even in small doses, diminished 
the activity of the stomach in the digestion of proteids. 
Gluzinski showed, ten years ago, that alcohol causes an 
arrest in the secretion of pepsin, and also in its action 
upon food. Wolff showed that the habitual use of alcohol 
produces disorder of the stomach to such a degree as to 
render it incapable of responding to the normal excitation 
of the food. Hugounence found that all wines, without 
exception, prevent the action of pepsin upon proteids. 
The most harmful are those which contain large quan- 
tities of alcohol, cream of tartar, or coloring matter. 
Wines often contain coloring matters which at once com- 
pletely arrest digestion, such as methylin blue and 
fuchsin.^ 

Blumenau says, '^ On the whole, alcohol manifests a 
decidedly unfavorable influence on the course of normal 
digestion even when taken in small quantities, and injures 
the normal digestive functions."^ 

REVIEW OF THE HYGIENE OF DIGESTION 

1. Cereals, vegetables, and fruit, with eggs and the dairy products, 
make a complete and perfect diet, though meat in moderate quantities 
may be added with advantage. 

2. Meat contains, besides proteids and fats, which may be fur- 
nished by a vegetable and dairy diet, some substance which seems to 
stimulate men to higher endeavors. For this reason a moderate 
amount of meat is desirable. 

3. If meat is eaten in too large quantities it makes people nervous 
and irritable, and more likely to su:ffer from neuralgia, rheumatism, 
or gout. 

1 J. H. Kellogg, M.D. 2 g. F. Mather, M.D. 



118 PHYSIOLOGY 

4. One may be intemperate in eating. One should eat only as 
much as is needed for nourishment, and eat at regular hours only. 
A very good rule to follow is to eat slowly and to stop eating as soon 
as one is satisfied. 

5. Eat to live, hut do not live to eat. 

G. Pure water is nature's drink for plants and all animals, includ- 
ing man. 

7. In the warm weather of spring and summer one may drink 
freely of such refreshing drinks as lemonade and other fruit-acid 
drinks. 

8. Nourishing drinks, such as milk, cocoa, chocolate, and the 
cereal coft'ees, are liquid foods, and should be taken only at meal 
times. 

9. Stimulating drinks, such as tea and coffee, are injurious to chil- 
dren and young people, and if taken in more than moderate quantities, 
are injurious to grown up people. There is much intemperance in 
the use of tea and coft'ee. 

10. Some people have claimed that alcohol is a food ; but the lead- 
ing scientists do not say that it is a food. 

11. Alcohol appears to stimulate at first, but it really lessens the 
brain control, the self-restraint, and the will power, besides dulling 
the senses and the sensibilities. Thus Alcohol is a true narcotic even 
in small doses. 

12. Scientists classify alcohol as a narcotic poison. It may take 
years for it to seem to injure the system. The only perfectly safe way 
to do is to abstain from alcoholic drinks altogether. 

18. DOMESTIC ECON^OMY 

Before we can decide what to buy for our tables, we 
must decide how much money we have to spend. In 
mechanical lines of work men earn from 11.50 to $4 or 
$5 a day, but in the cases where the higher wages are 
received there is usually a time in the year when work 
stops, so that an average pay would be about $2 a day 
throughout the year, or about $50 a month. Men in mer- 



NUTRITION 119 

cantile or professional lines receive salaries varying from 
8500 to 18000 or 110,000 but a large proportion of men 
in these lines of work receive about $1200 per year, so we 
will consider $100 a month a fair income. 

What are the items of expense for which every one 
must allow? Rent, clothes, food, and fuel one thinks of 
at once, but there are other equally important items to 
consider, such as insurance, savings, benevolence, house 
furnishings, and incidentals, which includes books, school 
expenses, and recreations. 

Let us suppose these families to consist of three grown 
people and two children, or two grown people and four 
children, or four grown people. What proportion of this 
money shall be given to each item of expense ? 

Do you think a man can afford to give one fifth of his 
income for a house in which to live ? He certainly can- 
not afford to pay any more than that ; and right here is 
the mistake most often made — the mistake of allowing 
too much for rent ; because increasing the size of the 
house increases the amount necessary for help, for fuel, 
for lighting, and for furnishing, and at once places one in 
the predicament of living beyond his means. Having 
then allowed what you think best for this item, it will be 
well to consider the item of food which must necessarily 
be a heavy expense, and will consume not far from a 
fourth of the income in the cases given. Must a man 
insure his life and must he save for the future ? Cer- 
tainly, he must provide for his family in case of his death, 
and for himself and family in case he lives beyond his 
working days. However small the income, this last item 
should receive something, if possible, and the best way to 
provide for this is to decide first how much must be saved, 
and then apportion the rest among the necessary expenses. 



120 PHYSIOLOGY 

The car fares, daily papers, magazines, school expenses, 
books, and recreations must come under the incidental 
account ; something must be allowed for replenishing the 
household furnishings, and there must be a fund from 
which Ave can draw to help others, to pay our obligations 
to church and society. 

PROBLEMS 

1. Let each pupil make out a budget of expenses on a 
basis of $100 a month or $1200 per year. Here are some 
of the questions which must arise for solution : Taking 
such a family as that described above, — (a) How much 
per month shall I pay for rent ? (5) How much per 
month for kitchen and dining room expenses ? (c?) How 
much for fuel and lighting ? (d^ How much for cloth- 
ing ? (^) How much for books, periodicals, and educa- 
tion ? (/) How much for works of charity ? (^) How 
much for the church ? (Ji) How much for insurance ? 
(i) How much to be put into the savings bank ? 

2. How much would your savings account amount to 
in thirty years at three per cent simple interest ? 

3. If each $1000 were withdrawn from the savings 
bank as soon as so much had accumulated, and put at six 
per cent interest, to how much would the total savings of 
thirty years amount ? 

4. If you were unable to work after the thirty years 
were passed, what would your annual income be at six 
per cent on savings, and three per cent dividends on 
insurance ? 

5. Make out a budget of expenses for a family of three 
to come within the limits of income. If the interest and 
dividends are insufficient, what will you do ? 



NUTRITION 121 

19. DOMESTIC ECONOMY (continued) 

Having disposed so easily of |100 a month, let us turn 
to half that sum, which is the average workingman's 
income, and see how much can be done with that. The 
family is the same in size, the members of the family are 
just as hungry, and indeed the father who works with his 
hands needs more food than does the one who works with 
his head. 

We have decided that the first item to be provided for 
is hotv much f 07* savings ^^ That should be not less than 
one fifth of the earnings and as much more as the health 
and self-denial of the family will permit. Then he must 
carry $1000 insurance for the benefit of his family. He 
will then have not more than 138 to be divided among 
the other items. As this family cannot have so much 
money as the one on ilOO per month to spend for food, 
and must at the same time have as much if not more 
nourishment, the question is reduced to one of food 
values — from what foods can the most energy and nour- 
ishment be obtained for the least money. 

Let us see if a family of five persons can live upon $10 
a month for food and still be well nourished. For how 
much can this family be warmly and comfortably clad ? 
In the selection of clothing on this salary, attention must 
be given to good wearing qualities and colors that will 
not fade and look shabby in a short time. Moreover, if 
the material has good wear in it, when it can no longer 
be used for the one who first owned it, it will make a 
warm garment for a smaller member. The ability of the 
mother to do her sewing in a neat manner, the careful 
saving of buttons to serve upon one garment after having 
first served upon another; the careful cutting over of 



122 PHYSIOLOGY 

garments for smaller members, in brief, the prevention of 
zvaste will make the difference here between comfort and 
discomfort, if but $10 are allowed each month for clothes. 

Now let me ask how much do you think you can spare 
for cigars and tobacco and for alcoholic drinks? You 
have already laid out all of your money in necessary 
things ; from which account will you cut off to allow 
yourselves the indulgence of this appetite which gives you 
nothing in return? For the man with $100 a month let 
us allow three cigars a day at five cents each or one a day 
at fifteen cents, which is as little as most men who use 
tobacco indulge in, and Ave have $4.50 a month for to- 
bacco. If added to that ten or twenty cents a day be 
taken off for alcoholic drinks, we must take off from $3 
to $6 more. Shall we reduce our rent $4.50 a month and 
our food from $3 to $6, or must we wear less comfortable 
clothing ? If we do not take it from these items, it will 
reduce our savings to an alarming extent. Besides, if 
the father of the family takes from $4.50 to $7 a month 
for the gratification of his particular taste, has not the 
family at large a right to an equal amount ? If they are 
allowed another $4.50 or $7 for candy, nuts, soda water, 
ice cream, and so forth, to be eaten between meals, we 
must either give up all idea of saving for the future, or 
we must cut our living expenses down another notch. 
When we have but $50 a month and have stretched every 
dollar to its utmost, where shall we cut off ten cents a 
day for beer and five cents a day for tobacco, neither of 
which will add anything to the general comfort, but all of 
which will take from the general supply ? 

From an economic standpoint alone, then, we are forced 
to the conclusion that the use of tobacco or alcoholic 
drinks by one or tAVO members of a family is a most 



NUTRITION 123 

foolish and wasteful proceeding. Furthermore, it works 
a very grave injustice upon the other members of the 
family. 

PROBLEMS 

1. Make out an annual budget on the basis of |50 per 
month. 

2. How much can you save annually ? 

3. To how much will the savings amount in thirty 
years ? 

4. What will the income be after the thirty years are 
ended and all money earning stops ? 

5. How much would a man pay out for tobacco in 
thirty years at fifteen cents per day ? 

6. HoAV much would a man pay out for drinks in thirty 
years at fifteen cents per day ? 

7. Knowing that drinkers are almost universally smok- 
ers, how much would the man in problem 6 spend in 
thirty years for drink and tobacco at thirty cents per day ? 

8. To how much would these expenditures amount (in 
5, 6, and 7) if each accumulated flOOO were put at interest 
at six per cent and left to accumulate until the end of 
the thirty year period ? 

20. domp:stic economy 

Thirty dollars a month will provide nourishing, attrac- 
tive food, with some delicacies, for a family of five persons 
whose income is a hundred dollars a month. 

Fifteen dollars a month will provide nourishing, attrac- 
tive food for a family of five persons whose income is fifty 
dollars a month. 

Food should be chosen with reference to its nourish- 
ment, digestibility, cost, and variety. 



124 PHTSTOLOGY 

Meat is the most expensive article of diet, and is usually 
eaten too freely. 

Soups are inexpensive, and with the addition of vege- 
tables or cereals can be made very nourishing. 

A variety of vegetables is advisable. 

Corn, as sweet corn, hominy, corn meal (which latter 
can be used in muffins, brown bread, pancakes, mush, 
puddings, and so forth), is a cheap and nourishing food. 

Fried foods should form a very small part of one's diet. 

The secret of good living at low rates is to buy food 
which is nourishing and in form easy to digest ; to buy 
each thing in its season, and to make good use of what is 
left over. 

I. TYPICAL ME:^rus 

Menu on ^30.00 per month basis. 

One of the first things to be determined in arranging a 
menu which must come within a certain monthly limit is 
to apportion the weekly allowance ($7.00 on above basis) 
and then determine how much of the weekly allowance 
must be expended for such general supplies as butter, 
flour, milk, sugar, potatoes, lard, coffee, fuel, and so forth. 
On a 17.00 per week basis one must allow about $3.00 
per week for these general supplies, something as follows : 
butter, 1.50; flour, $.25; milk, $1.00, sugar, $.25 ; pota- 
toes, $.15; lard, $.05; coffee, $.10; fuel, $.60; inci- 
dentals, $.10. 

TYPICAL MENU FOR OXE DAY 

Breakfast — Oatmeal ($.02), sugar and cream, waffles, 
maple sirup, cereal coffee. 

Luncheon — Omelet ($.10), bread and butter, milk. 



NUTRITION 125 

Dinner — Pork and beans ($.12), tomatoes ($.05), 
baked potatoes, brown bread and butter (f.05), baked 
apples and cream ($.05). 

On a $50.00 per month income, not more than $15.00 
per montli should be allowed for board. That brings one 
down to $3.50 per week for a family of five. Of this 
about $2.00 per week will be expended for such general 
supplies as milk, $.50; flour, $.35; sugar, $.25; butter, 
$.35; lard, $.10; cereal coffee, $.10; potatoes, $.25; sirup, 
$.10; incidentals, $.10. 

TYPICAL ME:^U for ONE DAY 

Breakfast — Bacon ($.05), potatoes, bread and butter, 
coffee. 

Dinner — Beefsteak (round, $.12), potatoes, bread and 
butter. 

Supper — Cream of onion soup ($.01), bread and butter. 

II. PROBLEMS 

1. Get a list of market prices for various staple articles, 
such as those mentioned under general supplies, also vari- 
ous vegetables, meats, cereal foods, and so forth. 

2. Find out from home or from the teacher the amount 
of the various supplies needed for a meal for five persons. 

3. Find the most economical way to choose the various 
cuts of meat. For example, some cuts, if large enough, 
will be sufficient for several days if used in made-up 
dishes like stews and meat pies for the last one or two 
meals. 

4. Make out a complete menu for a week on the basis 
of $7.00. 

5. Make out a complete menu for a week on the basis 
of $3.50. 



CHAPTER VL — CIRCULATION — HOW THE 
NOURISHMENT IS DISTRIBUTED 

1. THE NEED FOR A CIRCULATORY SYSTEM 

Nearly all of our study of physiology up to the 
present time has been devoted to the study of foods and 
their preparation, and to the process of the mastication 
and digestion of foods. 

After the food is digested, it is absorbed into the system 
from the alimentary canal and forms a part of the blood 
and lymph of the body. This blood and lymph is tissue 
and cell food. Every cell of the body requires food in 
order to enable it to do its work, and it requires a particu- 
lar kind of food. The cells of the body are working for 
their board and room, that is, for their nourishment and 
protection. Their protection is accomplished by their 
being colonized together in the body ; their nourishment 
is provided in a common stock of nutriment carried by 
the blood. The cells are constantly drawing their supply 
from this common stock, and the blood is just as con- 
stantly being replenished by absorption from the digested 
foods of the alimentary canal. 

The problems which we have to solve in this chapter 
are, first, what is the composition of the blood, and 
second, how is the blood distributed to the different cells 
and tissues. 

Let us now consider the general character of the dis- 
tributing system. Most of you are familiar with the 

126 



CIRCULATION 127 

method which cities and many towns use in distributing 
water to the different houses. You know that large 
mains, as they are called, or large tubes run from a 
central pumping station along the main thoroughfares of 
a city, giving off from time to time branches which pass 
along side streets and supply portions of the city not 
reached by the main channel ; finally, every house has its 
water pipes, and, after entering the house, the pipes sub- 
divide, each branch finally going to a faucet or other 
terminal fixture. When the faucet is turned, the water 
will flow with more or less force, and may be utilized for 
various household purposes, after which it is carried off 
first in small pipes that converge to one of considerable 
size, which leaves the building and passes to the street, 
where it empties into a still larger one. 

In a similar way the drainage or sew^erage of a whole 
city is collected in pipes of ever increasing size, and finally 
carried away from the eitj in large mains, to be emptied 
into some lake or river, and finally to the sea. From the 
sea the water is vaporized, carried in the form of clouds 
by the wind out over the land, where it falls as rain, and 
may be again used by a city, perhaps by the same city that 
used it at first, though it is not likely that any consider- 
able amount of the water so purified ever does actually 
come back to the same city which once used it ; and for 
this reason the water sewerage of a city cannot be called 
a circulatory system. 

In the animal body we have a striking analogy to a 
great city : first, in the need of individual cells for liquid 
and solid; second, in the actual distribution of this 
through a system of tubes ; third, in the collection of 
refuse matter or sewage of the system into another system 
of tubes ; fourth, the purification of the sewage. If the 



128 PHYSIOLOGY 

purified sewage of a city were returned and pumped 
through the same channels for the water supply, the 
analogy would be perfect, because in the animal body the 
purified blood passes into the pumping station and is at 
once sent out again through the system of supply tubes. 
This fact of the blood making the circulation of the body 
repeatedly, at one time carrying fresh liquid and food, 
and another time carrying refuse, has caused the whole 
sj'stem of tubes to be called a circidatorij system. 

As the stream of pure blood in its blood vessel, bring- 
ing both water and nourishment, enters a tissue, it at once 
divides into minute tubes called capillaries, which dis- 
tribute the blood to each part of the tissues. The blood 
does not actually empty out into the tissues, as is the case 
in a water tube that empties out from a faucet into a wash 
bowl, but the wall of the tube being thinner than tissue 
paper, there is a ready exchange between the pure blood 
within the capillary and the impure plasma outside, so that 
by the time the capillary has passed through the tissue, it 
has given to the tissue much that was pure and has taken 
up from the tissue much that was impure ; joining with 
many other capillaries, the stream passes out of the tissue 
charged with the impurities of tissue waste and tissue 
oxidation. 



2. THE BLOOD 

Fkom what we have learned, it must be clear that the 
blood is a very complex liquid, because it contains food for 
every tissue and cell of the body. Some tissues require 
proteid food, some fats and carbohydrates, while others 
require mineral food. The blood must also contain all 
the waste materials. The blood carries not only liquid 



CIRCULATION 



129 



food, but gaseous food, the gas being dissolved in the 
liquid, and not being in the form of bubbles. 

You have all seen blood flowing from a cut or from a 
bleeding nose, and know that it is red. Not all animals 
have red blood ; the oyster and the lobster have white 
blood; the common earthworm or angleworm has red blood, 
and all animals that have a backbone have red blood. 
There is a very great difference between the blood of 
the angleworm, however, and the blood of a frog. In the 
angleworm, the red color of the blood is due to a red 
pigment which is dissolved in the blood, as the red pig- 
ment of raspberries or currants is dissolved in a sirup, 
giving the sirup its red color. 

But the blood of vertebrates owes its red color to 
innumerable red bodies floating in the blood. These red 
bodies are called corpus- 
cles. A thin film of blood 
spread upon a glass and 
looked at under a high 
power microscope would 
look like Figure 28. In 
studying this figure you 
will notice first that there 
are two kinds of bodies 
floating in the liquid, one 
a smooth, discoidal body, 
and the other a granular, 
spherical body. The 
smaller discoidal bodies 
are the ones which contain the red pigment, and because 
of their color they are called red corpuscles. The granu- 
lar, spherical corpuscles are perfect cells composed of 
protoplasm, and containing one or more nuclei. This 




Fig. 28. — Blood corpuscles as they appear 
under the microscope: B, C, I), E, red 
corpuscles seen in different positions ; 
F, G, white corpuscles. Notice that at 
B, D, the red corpuscles have gathered 
in rouleaux like coins when shaken 
together. 



HALL'S PHYS. - 



130 PHYSIOLOGY 

form of protoplasm generally has the power of contract- 
ing, and so these cells have the power of changing shape, 
like the amoeba of which we studied under General Physi- 
ology ; and because of this power to change their shape 
they can creep through little pores or openings in the 
wall of the capillary, and when once free from the capil- 
lary they can creep through the pores between the cells 
of the tissue. These creeping, granular corpuscles are 
called white blood corpuscles. 

The red corpuscles are derived from nucleated cells, 
and may themselves be called modified cells, but they 
have not the power to change their shape, and all that 
they do is done passively and not actively ; that is, they 
are acted upon rather than active. 

Blood, then, is composed of a nearly colorless fluid 
called plasma, in which two kinds of cells are floating, 
the white cells and the red cells, or, as they are more 
frequently called, the white corpuscles and the red corpus- 
cles. The fluid part of the blood, the plasma, carries the 
liquid nutriment from the alimentary canal to the tissues. 
From this we should expect the plasma to contain pro- 
teids, carbohydrates, and fats, and so it does. The 
carbohydrate is the grape sugar, or dextrose, absorbed 
from the alimentary canal ; the fat is in the form of 
minute globules, while the proteid is in the form of 
albumen, similar to egg albumen, but much diluted with 
water. Besides these foods already named, there are water 
and mineral substances in solution. The minerals are, for 
the most part, those which are utilized in the building up 
of tissues. The plasma also contains many waste sub- 
stances, which are constantly being added to by the 
tissues and just as constantly being carried away by the 
excretory organs. 



CIRCULATION 131 

In a similar way the foodstuffs are being added to the 
plasma by absorption from the alimentary canal, and con- 
stantly being taken away from the plasma by the tissues, 
so that there are in constant progress two additions to the 
plasma and two subtractions from it ; still, the wonderful 
adaptation of the system and the delicate control by the 
nervous system result in keeping the plasma in nearly the 
same condition, varying more in tlie relative amount of 
water than in any other constituent. 

The work of the red blood corpuscles is to carry oxygen 
from the lungs to the tissues ; the work of the white 
blood corpuscles will be described later. 

3. HOW THE BODY IS PROTECTED AGAIXST EXCES- 
SIVE BLEEDING 

Every schoolboy knows that if he cuts his finger deeply 
the blood will come streaming out ; he knows, too, that 
the blood will flow only a short time and then stop ; he 
knows, too, that if the blood is allowed to collect upon the 
finger, not being rubbed off or rinsed off with water, that 
in two or three minutes it will form into a jellylike mass 
upon the finger, and if this jellylike mass is brushed away 
after the bleeding stops, he will find that the cut is filled 
with blood which seems to be in the same condition as 
that which he brushed away. 

This is nature's method of stopping the bleeding. The 
jellylike mass, which forms whenever the blood is exposed 
to the air after being shed, is called a ed-ctg' u-lum^ and the 
process of its formation is called coagulation. 

You will remember that in describing milk, when we 
were studying about foods, the milk separated into small, 
flakelike coagula on the addition of acid. Each little 



132 PHYSIOLOGY 

mass of the milk would be called a coagulum. You know 
that if milk is exposed to the warm air for a few hours 
on a summer's day it will turn into a jelly like mass simi- 
lar in consistency to the coagulum of the blood. The 
process which takes place in the milk is similar to the 
process which takes place in the blood during coagulation. 

Sweet milk contains a proteid called caseinogen. When 
the milk is exposed to the air, a ferment which floats in 
the air gets into it and causes a fermentation of the milk 
sugar, which results in the formation of milk acid, and 
that causes the caseinogen to be separated out in the form 
of casein. 

The blood contains several liquid proteids similar to 
the white of egg- One of these is called fibrinogen. 
When the blood is shed, and comes into contact with the 
air, or any foreign substance, a ferment Avhich is always in 
the blood, but which does not act when the blood is cir- 
culating within the vessels, begins to act upon the fibrino- 
gen, causing it to separate out into stringy fibers. These 
fibers form a network in whose meshes the red blood 
corpuscles and the fluid part of the blood are caught. 

In some animals the blood coagulates very quickly, and 
in some animals very slowly. The blood of insects and 
small birds coagulates almost instantly ; human blood 
coagulates in two to five minutes or more, according to 
various circumstances. The blood of horses coagulates 
in not less than five minutes. The coagulation is hastened 
when the blood comes in contact with foreign matter of 
any kind, and especially with air or with foreign matter at 
a temperature considerably higher than that of the body. 
If a deep wound is bleeding so freely as to endanger life 
from loss of blood, the coagulation can be hastened by 
binding over the wound absorbent cotton or linen. 



CIRCULATION 133 

If a boy were to lose a tablespoonful of blood he might 
be quite frightened, thinking that he was bleeding to 
death, bnt it has been found out by experiment that about 
one thirteenth of the weight of the body is blood, so that 
any person weighing ninety-one pounds would have nearlj^ 
a gallon of blood, and at least one third of this or more 
than a quart could be lost without in any way endanger- 
ing the life of the person. 

If a large blood vessel were cut, the blood might flow 
too rapidly to be stopped by coagulation alone, so that 
unless some prompt measures be taken a person might bleed 
to death in a few minutes. Just what to do in such an 
emergency will be described later, after we have described 
the blood vessels. 



4. THE ORGANS WHICH CAUSE THE BLOOD TO CIR- 
CULATE 

THE HEART 

Many of you have visited the village or city water- 
works, and have seen the great engine pumping the water 
through the system of tubes described in a previous lesson. 
When the pump stops, the water ceases to flow. In a 
similar way the blood is forced through the system of 
blood vessels by a pumping organ, the heart. When 
the heart pumps rapidly the blood flows rapidly, and when 
the heart pumps slowly the blood flows slowly. If this 
central pump were to stop its work, the blood would stop 
flowing. The cells all over the body would be deprived 
of their proper nourishment and oxygen, and would have 
to stop working. So we see how important an organ the 
heart is. 



134 



PHYSIOLOGY 



Figure 29 gives the outside view of the heart ; this 
shows the heart as it would look if we could look into 

the chest of another, and see 
the heart lying there so that 
what is on the right side in 
the picture (Fig. 29) would 
represent the left side in the 
body. 

Notice that the upper left- 
hand portion of the heart is 
a little earlike appendage ; 
this is called the left auricle 
(left ear). There is a much 
larger chamber at the upper 
right-hand part of the heart 
which is called the right 
auricle. 

These auricles are filling 
chambers for the heart, which 
hold the blood while the 
chambers of the 
forcing the blood 
arteries. These 
pumping chambers are two 
They make up 
the main body of the heart/ 
One of the chambers is di- 
rectly under the left auricle, 
and is called the left ventricle, 
while the chamber under the right auricle is called the 
right ventricle. 

The general relation of these chambers of the heart 
can best be shown by a diagram (see Fig. 30). 




pumping 

Fig. 29.— The heart and large blood heart are 
vessels, in front. 1, right ventricle ; into the 
2, left ventricle; 3, pulmonary ar- 
tery, cut short; 4, 4', 4", aorta, or 
chief artery ; 5, 6, parts of the right in number, 
and left auricle ; 7, 7, veins uniting 
to form the superior (upper) vena 
cava ; 8, inferior vena cava ; 9, vein 
from liver ; +, arteries nourishing 
the heart. 



CIRCULATION 



135 



Notice that the blood enters the left auricle through 
vessels from the lungs (pulmonary veins) ; that it passes 
from the left auricle into the left ventricle through the 
bicuspid valve ; when the left ventricle contracts and 
forces the blood back against the bicuspid valve, the 
valve closes, and the blood cannot get back into the auri- 
cle, but it can pass out into the aorta, and from the aorta, 
which is the largest artery of the body, the blood is dis- 
tributed all over the body, 
coming back to the heart 
from the veins, and enter- 
ing the right auricle. 
From the right auricle it 
can pass through the tri- 
cuspid valve into the right 
ventricle, and wlien this 
ventricle contracts, the 
cusps of the tricuspid 
valve are forced together 
and closed, while the valve 
into the pulmonary artery 
is forced open. 

The impure blood passes 
out to the lungs to be puri- 
fied, and after purification 
it returns through the pulmonary veins already referred 
to into the left auricle. 

The left side of the heart has to force the blood all over 
the system, while the right side of the heart has only to 
force the blood into the lungs which lie all about the 
heart in the thorax. For this reason the left side of the 
heart has a very heavy muscular wall, while the right 
side of the heart has a much thinner one. 




Fjg. 30. — Diagram illustrating the course 
of the blood through the heart. [Tracy.] 



136 PHYiSIOLOGY 

5. THE ORGANS WHICH CAUSE THE BLOOD TO 
CIRCULATE (continued) 

THE ARTERIES 

The tubes which conduct the water from the pump- 
ing system of the city to the various houses are composed 
of either stoneware or iron. The smaller subdivisions 
within the house which go to the different faucets are 
metal. 

The system of tubes which conduct the blood over the 
body begins at the heart with a large, thick-walled tube, 
a little larger than one's thumb. This tube is called the 
aorta. 

All of the tubes which carry blood away from the heart 
are called arteries. The aorta is the main trunk of this 
system of tubes. The accompanying plate (page 137) 
shows the aorta passing upward from the base of the 
heart, curving around at the base of the neck, and then 
passing downw^ard along the spinal column. Notice that 
it gives off branches as it passes downward and therefore 
becomes smaller and smaller, and divides into two main 
branches, one passing to each leg. 

The larger divisions of the aorta are those which pass 
to the legs and arms, next in size being those which pass 
to the kidneys (page 137). These large branches sub- 
divide into numerous smaller branches and twigs, the 
subdivisions passing outward in every direction, and 
carrying the blood stream to every portion of every tissue 
in the body. 

When the blood reaches the tissues which it is to 
nourish, the arterj^ subdivides into branches not larger 
than a needle. These little arteries are called arterioles. 



138 



PHYSIOLOGY 



The arterioles finally subdivide into a network of minute 
hairlike branches called capillaries. Many of the capil- 
laries are so fine that there is room for only one corpuscle 
to pass along at a time. These capillaries have walls so 
thin that the blood plasma can ooze through as the blood 
filters through the tissues. 

Several venules coming together form a vein, and one 
vein emptying into another will form a large venous 
trunk. Eefer to page 137^ and notice the venous trunk 
getting larger and larger as it passes toward the heart, 
receiving branches from either side. The large vein 
which passes up through the abdomen to 
the right auricle of the heart is the inferior 
vena cava; the one which comes down from 
the head and arms, emptying into the right 
auricle, is the superior vena cava. 

It has been mentioned above that the 
wall of the aorta is very thick and strong. 
It is composed mostly of very dense, 
strong, elastic fibers of connective tissue, 
but there are some muscular fibers in the 
outer portion of the wall of the aorta, and 
the wall is lined with a very thin mem- 
brane, thinner than tissue paper, composed 
of little platelike cells lying side by side, 
as shown in Figure 31. 
Fig. 31. — Lining of The Smaller arteries have a much thinner 
an artery or vein, ^y.j]^^ which is composcd largely of mus- 
cular tissue with only a little of the 
elastic connective tissue ; the lining is the same as that 
of the aorta. 

As we pass to the finer twigs of the arterial system, we 
find the muscular coat and the elastic coat becoming 




CIRCULATION 



139 



thinner and thinner ; finally in the capillaries only tlie 
inner coat remains, and, as has been stated above, this 
coat is so thin and delicate that the blood plasma can 
ooze through it as the blood 
is forced by the heart through 
the capillary network. (Study 
Figure 32.) 

The walls of the veins, al- 
though they are much thinner 
than those of the arteries, are 
made in the same way. That 
is, they are made of elastic 
connective tissue, muscular 
tissue, and the thin inside lin- 
ing. The veins have some- 
thing .which the arteries do 
not have, and do not need ; 

the veins have valves. These Fig. 32. -Capillary network show- 

mg now the walls are made of thm 

valves are so arranged that plate-cells. [Schaefer.] 
they open toward the heart. 

Thus they allow the blood to flow toward the heart, 
but do not allow it to flow back. If anything presses 
upon a vein, the blood may be hindered from continuing 
its flow toward the heart, but it cannot be pushed back 
into the cax)illaries. 

There are none of these valves in the veins of the neck 
and face, because they are not needed there in the usual 
positions of the body. 

When the body is inverted, as when one hangs wdth his 
head downward, the blood backs up or flows back into the 
venules and capillaries of the face and neck, making the 
skin flushed and almost purplish, if one keeps the position 
for some time. 




140 



PHYSIOLOGY 




6. THE CIRCULATION OF 
THE BLOOD 

The blood cannot circulate 
by any force of its own, but 
it is forced tlirougli the arterial 
system, the capillaries, and the 
veins by the pumping of the 
heart. If you will refer to 
Figure 33 you will find a dia- 
gram of the circulation ; the 
lighter portion represents the 
arterial system, the darker por- 
tion the venous system. 

This diagram represents 
what are called the greater 
and lesser circulations. The 
greater circulation is that 
which supplies the whole body 
with blood, beginning with 
the aorta Avith its numerous 
branches distributed through- 
out the system, and ending 
with the vense cavse which 
bring the blood back to the 
right auricle. 

Notice in the diagram that 
from the right ventricle the 
dark stream passes upward to 



Fig. 33.— Diagram of the circulation. 
1, heart ; 2, lungs ; 3, head and upper 
extremities ; 4, spleen ; 5, intestine ; 6, 
kidneys ; 1, lower extremities ; 8, liver. 
[Dalton.] 



CIRCULATION 141 

the lungs. This stream is the puhiionary artery, carrying 
impure blood ivoni the heart to the lungs, where it is 
oxygenated, after which it passes back to the left auricle 
through the pulmonary veins. This portion of the general 
circulation which carries the blood to and from the lungs 
is called the lesser circulation, or the lung circulation. 

Let us now follow the circulation in detail, beginning 
with the left auricle. Turn back to Figure 30 and notice 
that the blood flows into the left auricle from four pul- 
monary veins ; from the left auricle it passes through the 
bicuspid valve into the left ventricle. It passes into the 
left ventricle because the muscular walls of the left auricle 
contract and force it into the left ventricle. It does not 
require much force at first, because the left ventricle is 
empty ; all the force required is enough to swell out its 
walls. After the auricle has emptied itself into the left 
ventricle, the ventricle begins to contract. Its contrac- 
tion presses the blood up toward the base of the heart. 
This forces the valve together, thus closing the opening 
into the left auricle, so that no blood can get back that 
way. The ventricle keeps on contracting until the pres- 
sure against the valves into the aorta is sufficient to push 
them open and force the blood that was in the left ventri- 
cle out into the aorta. After the ventricle has emptied 
itself into the aorta and relaxes, the valves of the aorta 
clap together and hold the blood in the aorta while the 
ventricle is being filled again from the auricle. The 
contraction of the ventricle which throws the blood into 
the aorta is called the systole. 

Now turn to Figure 33 ; follow the blood from the left 
auricle into the left ventricle (marked 1) and from the 
left ventricle around the curve of the aorta. The diagram 
shows a large branch turning upward to the head and 



142 PHYSIOLOGY 

arms. This branch in the diagram really represents sev- 
eral different arteries, so that the diagram is intended to 
represent only the general features of the circulation. 
After giving off blood for the head and arms, the aorta 
turns downward through the thorax and abdomen, giving 
off many small branches that run between the ribs and a 
large one to the spleen (Fig. 33, 4), then there are large 
branches to the stomach and intestines (Fig. 33, 5), then 
branches to the kidneys (Fig. 33, 6), and, finally, branches 
to the legs (Fig. 33, 7). 

In all of these different organs to which the blood is 
supplied, it filters slowly through the capillary network 
and collects in venous branches corresponding to the 
arterial branches. Notice that the blood from the spleen, 
stomach, and intestines collects into a large venous trunk 
(marked by the white arrow), and passes to the liver 
(Fig. 33, 8). This is the portal vein. All the venous 
blood finally collects in the right auricle, whence it passes 
into the right ventricle (see also Fig. 30) ; the right 
ventricle contracts at the same time that the left ventricle 
does, and sends the blood through the pulmonary artery 
to the lungs (Fig. 33, 2), where it is oxygenated, after 
which it. passes to the left auricle, thus completing the 
circulation. 

The blood flows very rapidly in the aorta and the large 
arteries, but as it reaches the tissues and passes into the 
innumerable small branches the flow becomes very slow, 
thus giving a good chance for an exchange to occur between 
the blood circulating in the capillaries and the cells which 
border the capillaries. As the blood collects again in 
the venules and veins it begins to flow faster, and con- 
tinues to increase in its rate of flow until it reaches the 
heart. 



CIRCULATION 143 

6. THE CIRCULATION OF THE BLOOD (continued) 
I. THE PULSE 

If you put the tips of the fingers upon the wrist near 
the base of the thumb, you will feel a little throbbing. 
This throbbing is called the pulse. All the arteries throb 
or pulsate, but the pulsation of only those larger arteries 
which are located near the surface can be felt. If one 
puts the tips of his fingers just in front of his ear, he can 
feel the pulsation of an artery. A pulsation may also be 
felt on the side of the neck. 

What causes the pulse ? When the heart contracts, it 
throws about half a tumbler full of blood into the aorta ; 
this forces the elastic walls of the aorta to quickly stretch, 
and it starts a wave down the arterial system, a wave 
which follows all the branches of the arterial system clear 
to the farthest branches of the arterioles. This wave is 
called the pulse. 

When the physician presses his fingers upon one of 
these arteries, he can tell by the way it throbs whether 
the heart is beating rapidly or slowly, whether it is strong 
or feeble, and whether the smaller arteries are congested 
or relaxed. So much depends upon the condition of the 
heart and the circulatory system in general, that it has 
become customary for the physician to feel the pulse as 
one of his preliminary tests. 

II. PROTECTION AGAINST BLEEDING 

The reason that we do not feel the pulse at almost any 
part of the surface of the body is because most of the 
larger arteries are located far beneath the skin. These 
arteries are in the safest portion of the system; if they 



144 



PHYSIOLOGY 



were nearer the surface they might easily become wounded 
in some of the various injuries which the body suffers, 
such as a cut with a knife, and then the blood would flow 

so rapidly as to endanger the 
life of the person. Even with 
this protection large arteries or 
veins are sometimes cut. 

It is very important for every 
one to know what it is best to 
do when that happens. If the 
vessel is an artery, the blood will 
come in spurts because of the 
pulsations. To stop the bleed- 
ing of an arter}^ it is necessary to 
press against the trunk of the 
artery. This pressure must be 
between the bleeding end of the 
c ^j.. artery and the heart. 

The best method for making 

Fig. 34. — Manner of compress- this pressure is to take a hand- 
ing an artery with a ban dke^ kerchief by its corners, make it 
chief and stick. [Tracy.] -^ ' 

into a roll, and tie a single knot 
in the middle ; pass the handkerchief around the limb 
with the knot above the wound, and tie the ends so that 
the knot is not tightly drawn; put a stick through (a ruler 
or a lead pencil might serve the purpose) and then twist 
the handkerchief tightly enough to stop the bleeding 
(Figure 34 represents the handkerchief so applied). 




III. HOW THE BLOOD >^OURISHES THE TISSUES 



When the blood reaches the tissues and is slowly filter- 
ing through the fine capillaries, some very important 



CIRCULATION 



145 



things happen, in fact, the very things for wliich the 
whole circulatory system exists. 

The plasma of the blood oozes out througli the line 
pores between the cells of the capillary wall, carrying to 
the hungry cells which make up the tissue the food which 
they most need. Some of the fresh plasma passes into 
the tissue ; some of the plasma which was in the tissue 




Fig. 35. — Showing how white corxDUScles get through the walls of the 
capillaries. [Hall.] 



before, and from which a portion of the nourishment has 
been taken up by the cells, will pass out of the tissue 
through the lymph vessels, and, after passing through 
the lymph circulation, will finally pass back into the 
blood circulation. 

But this is not all that happens while the blood is pass- 
ing through the capillaries. Figure 35 shows under A 
the way in Avhich the blood corpuscles usually float 
through a large capillary; under B the figure shows what 
happens when there is something wrong in the cells wliich 



146 PHYSIOLOGY 

border the capillaries. The white corpuscles leave the 
center of the stream, pass to the capillary wall, put out a 
little arm such as shown in cells marked 2 (Fig. 35), 
force this arm tlirough a little opening in the capillary 
Avail, then gradually creep through the wall as sliown in 
the cells marked 3 (Fig. 35). 

When once they are free and in the cells of the tissue 
(see cells marked 4 in Figure 35), they put out little arms 
and creep about repairing any damages which the cells 
may have suffered. 

If a sliver has been thrust into the tissue, thej^ will 
gather about the sliver in such great numbers as to 
make a soft covering, thus protecting the tissue from 
further damage by the intruder. If microbes have got 
in, the white corpuscles will eat up the microbes, thus 
in most cases protecting the rest of the tissue from the 
action of these parasites. Sometimes, however, there are 
too many microbes or bacteria to be thus disposed of, 
when they will accumulate in the system and cause a 
fever or some disease. 



lY. W^HERE THE BLOOD LOSES ITS OXY^GEN 

We have mentioned how the blood becomes oxygenated 
in the lungs. It leaves the lungs in a bright scarlet 
stream ; it retains this appearance until it comes to the 
capillaries, where it gives up its oxygen to the hungry 
tissues. 

As soon as it loses its oxj^gen, it loses its bright scarlet 
color, becoming dark purplish red, which color it retains 
throughout its course through the venous system back to 
the heart (Fig. 36). 



CIRCULATION 147 



7. THE LY.MPH AXD ITS CIRCULATION' 

At the end of the previous lesson we were studying the 
changes which take phice in the blood during its passage 
through the capillaries. We found that blood plasma, 
laden with food for the cells, passes through the pores in 
the capillaries and oozes through tlie tissue, through the 
spaces between the cells. 

We found also that the white blood corpuscles pass out 

Capillary Neticoric 




Fig, 36. — Capillary network showing change from arterial to venous blood. 

through these little pores in the capillary walls. They 
pass out in large numbers only when there is some con- 
dition in the tissues which they can correct. 

But they are continually on the lookout for danger, and 
an occasional white blood corpuscle may pass through the 
capillary at any time, so that there are always some white 
blood corpuscles in the tissue spaces. 

The plasma and white corpuscles make up what is 
called tissue lymph. The tissue lymph soon becomes 
changed by the addition of substances thrown out through 



148 



PHYSIOLOGY 



the cells of the tissue, so that tissue lymph does not retain 
the same composition that the blood plasma had. As the 

plasma keeps coming into the 
tissues from the capillaries, it 
forces the plasma on and keeps it 
moving. After oozing through 
the tissue into which it first passed, 
it soon finds its way into little 
vessels which are like veins, except 
that they contain only lymph 
(Fig. 37). 

Once the lymph enters a vessel 
called a lymphatic, it may be called 
circulatory lymph ; it does not 
again enter the tissue, but con- 
tinues to move through lymphatics 
toward the heart in a way quite 
similar to that in which the venous 
blood moves toward the heart 
from the tissues. Small lym^Dhat- 
ics come together and make larger 
ones, until finally a very large 
lymphatic vessel passing up 
through the abdomen and thorax 
receives the lymph from the other 
lymphatics, and finally ]30tirs it 
into the venous system. 

In Figure 37, notice the little 
lymphatic glands which lie in the 
course of the lymphatics at 2. 
These glands are made up of a 
fine network of fibers, in the meshes of which there are 
innumerable little cells. As the lymph filters through 




Fig. 37. — Lymphatic vessels 
of the surface of the arm. 
1, ducts; 2, glands. 



CIRCULATION 149 

one of these glands, some of the white corpuscles which 
have become old and sluggish in their movements, get 
entangled in the network and die. 

But the lymph which leaves the gland has more white 
corpuscles than that which enters the gland, because 
young corpuscles are being constantly formed in the 
gland, so that a lymph gland is at the same time the 
grave of old white corpuscles and the birthplace of young 
white corpuscles. 

Looking again at Figure 37, you will notice that the 
larger lymphatics seem to have little joints, or nodes. 
The nodes show where the valves are located. What is 
the use of the valves ? The pressure of new blood plasma 
filtering into the tissue is sufficient to keep the tissue 
plasma moving, but it is not always sufficient to make the 
lymph pass up through the lymphatics to the heart. These 
valves are open toward the heart, allowing the lymph to 
flow easily in that direction, but they close as soon as the 
lymph is pressed back, and do not allow it to flow away 
from the heart. 

Now in the movements of the body^ especially of the 
arms and legs, the lymphatics are pressed uj)on by the 
contracting muscles. This pressure forces the lymph out 
of the lymphatics toward the heart because it cannot go in 
the opposite direction, thus leaving the lymphatics empty 
and ready to fill very easilj^ from behind as soon as the 
pressure is relieved. 

From this it must be clear that muscular movements of 
the legs, arms, and body assist the lymph circulation (it 
may be added here that it assists also the circulation in 
the veins), and in that way assists the nutrition of the 
tissues. In fact, the secret of the influence of muscular 
exercise upon the general health lies more in its action 

hall's phys. — 10 



150 



PHYSIOLOGY 



upon the lymphatic and venous circulations than in any- 
thing else. 

An important part of the lymphatic system is that 

which collects the tis- 
sue fluid from the in- 
1^^^ testine, carrying it to 

the thoracic duct (Fig. 
38). This portion of 
the lymphatic system 
.... /-„^ differs from the rest 

i ( //w^ in carrying absorbed 

foods from the intes- 

,C /pt tines to the circula- 

rWMf tory system. 

r MMli^ j^^I^il^^^ "^^^^ veins of the in- 

testine carry part of 
■ifij^^^^^^^^^^^^B the food, but the lym- 
/•MSP^^^^^^^^^^ft^ phatics carry all of 

^ JS^^^^^^^^^^^^K the absorbed fat. This 
' ^.v i^^^^^^^::^^^!^^ £^^ -^ ^^ ^j^^ form of 

an emulsion something 
like cream, and makes 
the lymphatics of the 
intestine look white, as 
'*"*-.,.^ / though they were filled 

with milk. For this 

Fig. 38. — Lacteals, thoracic duct, etc. a, in- . 

testine; b, vena cava inferior; c, c, right rcaSOn tiiese particular 

and left subclavian veins ; d, point of open- lymphatics have been 

ing of thoracic duct into left subclavian. t 

[Daiton.] called lacteals (from 

the Latin lac^ milk). 
This white lymph is sufficiently different from the rest 
of the lymph of the body to have a separate name ; it is 
called eJiyle, 




CIRCULATION 151 

8. THE CONTROL OF THE CIRCULATION 
CONTROL OF THE HEART 

Put your finger upon your pulse and count the number 
of times it beats in a minute. Count it again and see if 
you can make it beat faster this time than before. You 
will probably find, if you have been sitting still during 
your counting, that it beats just about the same from 
minute to minute, and that you cannot of your own will 
make it beat faster or slower. Now if you will lie down 
upon a bench or couch, and breathe very deeply and very 
slowly for five or ten minutes, and let some one else count 
your pulse, you will find that it is slower than it was 
at your first observation. 

If you take some brisk and vigorous exercise, like run- 
ning up and down a flight of stairs two or three times, or 
running around the schoolhouse two or three times, you 
will find that the heart is beating very much more rapidly 
and strongly than at your first observation. 

This experiment teaches us two things. First, that we 
cannot directly control the heart by the will, and, second, 
that there is something in the body that does control the 
heart. If we wish to make the heart beat faster, we can 
do so by making the other muscles of the body exercise, 
or if we wish the heart to go more slowly, we can accom- 
plish it by decreasing the work which it has to do for the 
system, which was done in the experiment above when 
you lay down in absolute rest and in a position which 
reduced the work of the heart. 

The heart, like the stomach, is controlled by the nervous 
system. There are two sets of nerves which go to the 
heart from the central nervous system. One of these sets 



152 PHYSIOLOGY 

of nerves comes from the sympathetic nervous sj^stem, 
and the other comes direct from the brain through the 
vagus nerve, which passes down the side of the neck, 
through the thorax into the abdomen. As the vagi 
nerves pass the heart, they give off branches to it. The 
nerves which come from the sympathetic nervous system 
pass to the heart from the upper ganglia of that system, 
as shown in the diagram of the sympathetic system (Fig. 
19, p. 51). e 

The nerves which influence the heart are shown in that 
figure to come from the first dorsal ganglion of the sym- 
pathetic system of both the right and left side, and also 
from the right and left vagus. From these various 
sources, the nerve fibers form a network near the base 
of the heart, called the cardiac plexis, or heart network. 

The nerve fibers from the sympathetic system cause the 
heart to go faster, while the nerve fibers from the brain 
make the heart go more slowly. These two sets of fibers 
are similar to the lines and whip which the driver uses in 
driving his horse, — the whip making the horse go faster, 
and the lines holding him back. If the whip is lost, the 
horse may go very slowly, and the driver has no way of 
making him go faster. Similarly, if the sympathetic 
nerves leading to the heart are cut, the heart will go very 
slowly, and any urgent need of the system for more blood 
will not be responded to by the heart, because the only 
impulse which it can receive from the central nervous 
system will only make it go more slowly instead of more 
rapidly. 

On the other hand^ if the nerves which the heart re- 
ceives from the vagus should be cut, the heart would begin 
to beat very rapidly, and the system would have no means 
through which to control it ; and like a horse whose lines 



CmCULATION 153 

are cut, it will go faster and faster until a disaster occurs. 
But .when these nerves are all in order, the heart will beat 
slowly when the tissues of the body need little blood, and 
will beat rapidly when the tissues of the body need more 
food or more oxygen. 



9. THE CONTROL OF THE CIRCULATION {continued) 
CONTROL OF TISSUE SUPPLY 

In the preceding lesson it was explained how the heart 
is made to beat more rapidly and strongly when more 
blood is needed in the tissues, but no mention was made 
of the very important fact that not all of the tissues need 
an extra supply of blood at the same time. When one is 
taking vigorous muscular exercise, he is not likely to be 
doing much thinking, nor is he likely to be digesting a 
meal, so it is the muscular system alone that needs an 
extra supply of food and of oxygen. When the stomach 
is digesting a meal, it needs an extra supply of blood. It 
can do its work to better advantage if it can for a time, 
say for an hour at least, monopolize in a measure the blood 
flow, not having to divide Avith muscles or brain. In order 
to accomplish this, the system has a very remarkable appa- 
ratus, which consists of muscles and nerves. The mus- 
cles are those located in the walls of the arteries, especially 
in the smaller branches of the arteries, and the nerves are 
fine fibers from the sympathetic nervous system, which 
pass to these muscles in the walls of the arteries, and 
either cause them to constrict the arteries, allowing less 
blood to pass, or causing them to dilate widely. 

Let us call the nerves which cause them to contract, 



154 PHYSIOLOGY 

vessel constrictors^ and those which cause the arteries to 
dilate, vessel dilators. 

When the stomach and intestines receive food which 
they have to digest, the dilators of the arteries supplying 
these organs cause the muscles of the arteries to relax, and 
the supply of blood will be increased in those organs only, 
while the amount of blood which passes to other organs 
in the system will be somewhat diminished. 

As another example, when one begins to perform vigor- 
ous exercise, or do hard work, the dilators of the muscular 
arteries will cause these arteries to dilate, thus increasing 
the flow of blood to the muscles. 

The muscles make up so much of the tissues of the 
body that a dilation of the muscular arteries would cause 
a considerable fall in the pressure of the blood, if the cen- 
tral pump, namely, the heart, did not increase the rate 
and force of its pumping. Thus it occurs that muscular 
exercise leads always to an increase in the rate and force 
of the beating of the heart. 

The heart is less modified in its beating by the work 
which the glandular organs or the brain may have to do, 
but that is because the glandular organs and brain make 
up so small a portion of the whole body. 

The influence of these constrictors and dilators upon 
the arteries may be very readily observed by noticing the 
skin. When one goes from a warm room into cold atmos- 
phere, the skin becomes white, and one feels chilly. That 
is because the little arteries of the skin have all been con- 
tracted by the constrictors, thus not allowing the blood to 
flow into the skin, but keeping it in the deeper organs and 
tissues. This is nature's method of keeping the blood 
warm. One's natural impulse, under such conditions, is 
to hurry, to move briskly. This brisk movement can 



CIRCULATION 155 

be carried on only through an oxidation of food materials 
within the muscle cells. But this oxidation causes heat 
to be given off to the blood. In a few minutes, if the 
system is in a perfectly healthy condition, the dilators to 
the arterioles of the skin will act, and the now heated 
blood will go into the skin and make it red and warm. 
If, for any reason, the blood remains in the skin at first 
without being withdrawn to the muscles and internal 
organs, it will be rapidly cooled down before the muscles 
have had a chance to heat it up through oxidation, as 
above described, and the temperature of the body will be 
lowered. 

The nerves which assist in the control of the arteries 
come from the sympathetic nervous system and are much 
influenced by the emotions. You have all noticed how 
the face flushes when one is embarrassed ; this is due to 
the action of the dilator nerves. Various emotions may 
cause the flushing or blushing, for example, anger and 
shame. Certain emotions, such as fear or extreme rage, 
may cause the constrictors to act, making the face white. 



10. THE HYGIENE OF THE CIRCULATORY FLUIDS AND 

ORGANS 

I. EXERCISE 

When the muscle tissue is at perfect rest the blood 
stream is comparatively slower, and the pressure of the 
blood in the capillaries is not sufficient to cause a large 
amount of plasma to filter through the capillary walls. 
There is, therefore, a smaller amount of tissue plasma 
or tissue lymph circulating between the cells. As a 
further result, the stream of lymph which leaves the 



156 PHYSIOLOGY 

muscle tissue by way of the lymphatics is also much 
decreased during inactivity. And the lymph which 
makes its way into the lymphatics, having little pressure 
from the tissue and little or no pressure upon the lym- 
phatic vessels from muscular contraction, moves only very 
sluggishly toward the heart. This sluggish flow of lymph 
during rest permits waste matter to collect in the tissue 
plasma. 

One or two periods of vigorous muscular exercise each 
day will, by increasing the flow of blood and lymph through 
the muscles, cause all this waste material to be carried 
out of the muscles to the organs of excretion, where it 
will be thrown out of the body. 

We see from this how important it is for one to take 
exercise. The increased strength and rate of the heart- 
beat during exercise will cause an increa^sed flow of blood 
in other tissues of the body as well as the muscle tissues, 
thus insuring the thorough sweeping away of waste 
material as well as a thorough distribution of the nourish- 
ment and oxygen contained in the blood. 

Most people who live in cities and towns do not exer- 
cise enough, and some people exercise too much. Some 
people wish to exercise, but there may be reasons why 
they cannot do so. 

II. MASSAGE 

Such people may substitute massage for exercise. The 
movement of the muscles of an arm or leg, or pressure 
upon the tissues of arm or leg or body, will cause an 
increased flow in the lymphatics and veins, even when 
some one else takes hold of the arm or leg and moves it 
for one. 



CIRCULATION 157 

This passive exercise is called massage, and is an im- 
portant means of insuring nutrition and an elimination of 
waste materials in inactive tissues. 

The most efficient kind of massage is kneading of the 
tissues and rubbing. If a boj^ has so-called ^'growing 
pains," which is really rheumatism from some exposure 
to wet or cold, his pains will be much relieved if the 
aching part is thoroughl}" rubbed or pressed, always 
beginning at the most distant part and working toward 
the heart. 

This will gradually work out the lymph and venous 
blood from the tissues and cause fresh blood to circulate 
through the tissues, carrying away from them those waste 
materials which are irritating the nerves and causing 
the pain. 

III. TIME FOR REST AND TIME FOR WORK 

We found that vigorous exercise takes most of the 
blood to the muscles. The digestion of a heavy meal 
takes most of the blood to the digestive system, while 
heavy brain work takes a large portion of the blood to the 
brain. 

Every onel^nows that it is impossible to do hard think- 
ing and hard muscular work at the same time. The 
reason is, that the muscles take the blood and leave the 
brain without sufficient supply of nutriment or oxygen to 
carry on its work vigorously. 

Whenever the muscular system is working hard at the 
same time that some other system of organs is attempting 
to do its work, the muscular system gets the blood, and 
the other system is robbed of the supply necessary to do 
its work properly. 



158 PHYSIOLOGY 

If one attempts to do heavy work after a heavy meal, 
he may do the work, but the meal either will lie undi- 
gested or will digest very slowly. Oft repeated attempts 
of this kind will so derange the digestive system that it 
refuses to do its work properly, and we say the person 
has indigestion or dyspepsia. A very light meal of very 
easily digested food may be followed almost at once by 
vigorous exercise, without causing serious injury to the 
digestive organs. A heavy meal should be followed by 
at least an hour of rest, or at most very little exercise 
in the open air. 

IV. THE CONDITION OF THE BLOOD 

You see how important it is for the health and strength 
of the body that the blood should always contain suffi- 
cient nutriment for the tissues, sufficient oxygen for tissue 
oxidation, and should be kept free from accumulated waste 
materials. 

One of the most frequent diseases of the blood is called 
anaemia, and consists of a decrease in the number or in 
the quality of the red blood corpuscles. The red blood 
corpuscles carry oxygen to the tissues; if these are de- 
creased in number the tissues will suffer for want of 
sufficient oxygen. 

The best way to avoid ansemia, or the best way to 
recover from it, is to eat plenty of nourishing food. It 
is understood, of course, that the digestive system is in 
good condition, otherwise the plenty of nourishing food 
could not be properly utilized by the system. f'oods 
which are rich in iron should form an important part 
of the dietary ; such foods are eggs, the cereal foods, 
beans, peas, spinach, and so forth. 



CIRCULATION 159 

11. THE INFLUENCE OF NARCOTICS UPON THE CIRCU- 
LATORY FLUIDS AND ORGANS 

I. THE EFFECT OF ALCOHOL UPON THE BLOOD 

Alcohol is absorbed from the alimentary canal un- 
changed by the processes of digestion. It passes into the 
blood vessels in the walls of the stomach and intestines, 
and is distributed by the blood throughout the system. 
Dr. Woodhead, Professor of Pathology, Cambridge Uni- 
versity, England, believes from the Avork of various 
medical men, whose authority he quotes, that the white 
blood corpuscles are injured by the presence of alcohol in 
the blood, and made less active in their work of defend- 
ing the system against the germs of disease, therefore leav- 
ing the system more exposed to various germ diseases. 

II. THE EFFECT OF ALCOHOL UPON THE HEART 

The occasional and moderate use of alcoholic drinks 
influences the action of the heart. " Wherever a distinct 
effect is made upon the system by alcohol, this is always 
indicated by the pulse. The action of the heart is quick- 
ened for a time, afterward becoming enfeebled until 
another dose of poison is taken to revive it. In time, this 
becomes the ordinary condition, and is accompanied by 
general changes in the action of the whole circulatory 
system. These changes in the action of the heart and 
arterioles lead to changes in the structure of the heart 
and blood vessels." ^ 

Professor Destree ('' Influence of Alcohol on the Muscu- 

iGeo. H. McMichael, M.D., Buffalo, N.Y., in the Dietetic and Hygienic 
Gazette, May, 1897, p. 278. 



160 PHYSIOLOGY 

lar System ") believes that the increased action of the heart 
under the influence of alcohol is only apparently a stimu- 
lation, resulting partly from the paralysis of the muscular 
Avails of the arterioles, thus allowing them to dilate and 
reducing blood pressure, which the heart tries to correct 
by beating more rapidly, and resulting partly from irri- 
tation of the mucous membrane of the stomach by the 
alcohol. This irritation affects the heart through the 
sympathetic nervous system. 

But the heart is not only modified in its action by the 
influence of alcohol, it is also modified in its structure. 
" The heart, from continued overaction, becomes dilated, 
and its valves are relaxed. The membranes which en- 
velop the organ are thickened, rendered cartilaginous, 
and occasionally calcareous. The valves, which consist of 
folds of membrane, lose their suppleness and become 
diseased and weakened. The muscular fiber of the heart 
is replaced by fatty cells, so that the power of contraction 
is greatly reduced. These derangements are liable to 
cause death from sudden failure of the heart itself, from 
rupture of the blood vessels, from oozing of the blood in 
the brain, producing apoplexy. . . . There is always 
danger of the heart failing to do its work, for alcohol has 
made it inefficient." ^ 

in. THE EFFECT OF ALCOHOL UPON THE BLOOD VESSELS 

From what has been said in a previous lesson about the 
muscular walls of the arteries and arterioles, it is plain 
that it is very important to the system that the arteries 
retain their power to respond quickly to the needs of the 
system, now expanding, and now contracting. But under 

iG. H. McMichael, M.D., Journal of Inebriety , July, 1897, p. 258. 



CIRCULATION 161 

the influence of alcohol, even when used in moderate 
quantities for a long period of years, the walls of the 
blood vessels become changed, especially the arteries and 
arterioles. The connective tissue of the arteriole Avail 
becomes much increased, thus making the wall thick and 
inelastic. Frequently lime salts are deposited in this 
connective tissue, making the wall of the artery brittle 
and liable to burst when there is any unusual strain put 
upon it. Now this weakening of the walls of the blood 
vessels is especially frequent in the arteries of the brain. 
Upon the occurrence of anything which causes a sudden 
increase in the heart's action, thus forcibly distending the 
arteries, rupture is likelj^ to occur, thus causing hemor- 
rhage of the brain, taking the form either of apoplexy or 
paralysis. 

IV. THE EFFECT OF TOBACCO ON THE HEART 

Dr. J. W. Seaver, a professor in Yale University, in 
an article on '' The Effects of Nicotine," calls attention to 
the fact that the heart action is increased when tobacco 
is being used, that the increase is due, not to stimulation 
of the heart, but to partial paralysis of the vagi nerves. 
From previous lessons you know that the vagi nerves hold 
the heart in check, causing it to reserve its power as much 
as possible for legitimate emergencies; now if the vagi 
nerves are paralyzed, the heart beats rapidly, thus unneces- 
sarily wearing itself out. With this information we can 
easily understand how in the beginning of the habit of 
smoking, the influence of the nicotine causes so much 
disturbance to the circulation, for the vagus is the great 
controlling nerve of the heart, and that organ is the first 
to respond to the poison. 



162 PHYSIOLOGY 



REVIEW OF THE CIRCULATION 

1. The body needs a system of tubes through which the liquids of 
the body can circulate, just as much as a city needs a system of tubes 
and pipes through which the water can circulate and the drainage 
and sewage be carried away. 

2. The blood and lymph are the liquids which circulate through the 
bod}^ The blood is composed of plasma in which float red and white 
cells or corpuscles. The lymph is composed of plasma in which float 
white cells or corpuscles, 

3. The Uood and lymph carry food to the working cells, tissues, and 
organs of the body. 

4. The blood and lymph carry waste matter from the working cells, 
tissues, and organs of the body to the place where this matter is to be 
thrown out of the body. 

5. If a blood vessel is cut, the blood clots or coagulates and stops the 
wound ^ unless a large artery or vein is cut. 

6. The blood is carried to different parts of the body in arteries 
and brought back in veins. It oozes through fine capillaries as it 
passes through the different tissues. 

7. The heart pumps the blood through the arteries, capillaries, and 
veins. Each contraction of the heart — each heart beat — sends blood 
into the arteries. Valves at the entrance of the aorta keep the blood 
from flowing back into the heart while the heart is being filled with 
the blood from the veins. 

8. When the heart forces blood into the arteries, it starts a little 
wave along all the arteries. One can feel this wave wherever the 
arteries com*e near to the skin. This wave is called the Pulse. Where 
may pulses be* felt ? 

9. The blood carries oxygen from the lungs to the tissues, and car- 
bon dioxide from the tissues to the lungs. 

10. The heart is controlled by two sets of nerves : one set (sympathetic) 
makes it beat faster and stronger, while the other (vagus) makes it 
beat more slowly. If the vagus be stimulated, the heart will beat 
more slowly; if the sympathetic nerve be stimulated, the heart will 
beat more rapidly. If the vagus be cut or narcotized, the heart will 
beat faster; if the sympathetic be narcotized, the heart will beat 
more slowly. 



REVIEW OF THE CIRCULATION 163 

11. The arteries are controlled hy two sets of nerves. The Constrictors 
make the arteries smaller and allow less blood to flow into the tissues. 
The Dilators make the arteries larger and allow more blood to flow 
into the tissues. 

1*2. When one exercises his muscles, the vessel dilators allow more 
blood to flow to the muscles. The heart also works harder and sends 
a faster current of blood over the body. One should not exercise 
severely just before or just after a meal. Every one needs exercise in 
the open air. 

13. Nourishing food and out-ofdoor exercise, with ic ell-ventilated homes 
and schoolrooms, will keep the blood pure and the body healthy. 

14. People who use alcohol are more subject to disease than are those 
who do not ; because the body, especially the blood, is less resistant to 
the germs of disease. 

15. Alcohol makes the heart beat faster ; because it narcotizes or dulls 
the influence of the vagus nerve. Explain how this can be. 

16. Alcohol makes the blood vessels of the skin dilate, and so the skin 
looks red and the person feels warm; but the blood gives up its 
warmth to the air, and the temperature of the body falls= Alcohol 
also causes the walls of the blood vessels to become weak. 

17. Tobacco causes the heart to beat faster than usual because the 
vao'us nerve is narcotized. 



CHAPTER VII. — RESPIRATION — HOW THE 
BLOOD IS PURIFIED 

1. THE NEED FOR A RESPIRATORY SYSTEM 

In our study of the plant we found that oxygen is 
necessary for its life processes ; that the energy required 
by the little germinating plant to push aside the little 
particles of soil and appear above the surface of the 
ground, can be obtained only by oxidation of some of the 
plant material. 

The oxygen which enters into the oxidation comes from 
the atmosphere ; the material oxidized is part of the plant 
body, and the result of the oxidation is liberated energy 
and waste products, comprising in the plant especially 
water and carbon dioxide. 

In a one-celled animal such as the amoeba, we found 
the same general principles to be true, and that every 
motion of the amoeba required an oxidation of a portion 
of the substance of the little animal, the oxygen coming 
from the surrounding medium, the oxidation resulting in 
the formation of waste products, among which carbon 
dioxide and water take a prominent part. 

Every active cell in our bodies requires oxygen in order 
to enable it to do its appointed work. If it is a muscle 
cell, the energy of heat and motion which it must generate 
for the body can only come from the oxidation of muscle 
cell protoplasm or muscle cell sap. If the cell is a gland 
cell, it cannot doits work of forming new substances with- 
out the presence of ox)^gen, which takes part in the changes 

164 



RESPIRATION 165 

that the cell makes in the substances which it absorbs 
from the blood. If it is a brain cell, oxygen is just as 
necessary, though perhaps used in somewhat smaller quan- 
tities than would be the case in a muscle cell. 

Respiration is the process of furnishing oxygen to the 
active cells of the body. The one-celled plants and ani- 
mals need no apparatus to carry the oxygen to the differ- 
ent parts of their system, because their minute bodies are 
surrounded either by the atmosphere, which is one fifth 
oxygen, or by water, in which oxygen from the atmosphere 
is freely dissolved. But in all animals except the simplest 
ones, large portions of the body are so far removed from 
contact with the atmosphere or water that these animals 
require a special apparatus or system of organs devoted 
to this work of supplying the inside tissues of the body 
with oxygen. This function is called respiration, and the 
system of organs which performs this function is called 
the respiratory system. 

Animals that live in the water breathe by means of gills ; 
animals that live on land breathe by means of lungs. 
Some animals live in the water Avhen they are young, and 
change and turn into land animals when they reach ma- 
turity. Such an animal is the frog : the tadpole breathes 
with gills, but the frog breathes with lungs. Some ani- 
mals which live in the water do not remain under water 
long at a time. The turtle and the crocodile are water 
reptiles which breathe by means of lungs. The whale, 
the seal, and the walrus are water mammals that breathe 
with lungs ; none of these animals can stay under water 
for a long period. 

Every one has seen the gills of a fish, and will remem- 
ber that they are composed of delicate, velvety branches 
which are protected behind a scalelike shield on the side 

hall's phys. 11 



166 PHYSIOLOGY 

of the fish's head. The fish draws water into the mouth, 
and closes the mouth, but instead of swallowing the water, 
presses it out the sides of the pharynx so that it passes 
over the gills which absorb the oxygen held by the water 
in solution. 

The lungs are elastic air sacs, which are made of very 
delicate tissue and lodged within the body cavity. The 
animal draws the air into the lungs, where it remains for a 
short time giving up its oxygen to the blood which is cir- 
culating within the capillary branches of the pulmonarj^ 
artery. The drawing in of the air is called Inspiration^ 
and the throAving of the air out of the lungs is called 
Expiration, 

That part of respiration which includes the inspiration 
of the air, the absorption of the oxygen, and the expiration 
of the air laden with carbon dioxide, is called external res- 
piration^ while that part of the respiration which includes 
the distribution of the oxygen to the tissues by the blood 
and the absorption of the oxygen from the blood by the 
tissues, also the giving up of carbon dioxide to the blood 
by the tissues and the transportation of this carbon 
dioxide gas by the blood to the lungs, is called internal 
respiration, 

2. THE ORGANS OF RESPIRATION 

The lungs have already been mentioned as organs of 
respiration, and they are the most important organs of the 
respiratory system. Figure 39 shows the lungs within the 
chest or thorax. Notice from the figure that there are 
two lungs, one on either side of the heart. These lungs 
are hollowed out to make a space for the heart. 

The pulmonary artery (i>) branches under the arch of 
the aorta, sending part of the blood to each lung. The 



RESPIRATION 167 

heart is not in the middle of the thorax, but just a little 
more on tlie lef t side than on the right, so that the left lung 
is a little smaller than the right lung. The two lungs and 
the heart rest upon the muscular partition which separates 
the thorax from the abdomen. This muscular partition is 



Fig. 39. — The cavity of the chest, showing the positions of the heart and the 
lungs. A, left lung; B, heart; D, pulmonary artery; E, trachea, or wind- 
pipe. [Tracy.] 

called the diaphragm. Notice from the picture that the 
diaphragm is higher in the middle than at the edges; in 
other words, it is arched upward. As the diaphragm is 
the principal muscle for drawing air into the lungs, w^e 
must name it among the respiratory organs. The air is 
carried to the lungs through a large tube in the neck 
called the windinpe^ or trachea. The upper part of the 



168 PHYSIOLOGY 

trachea is the larynx^ or Adam's apple which one can feel 
in the throat. 

The air in passing into the trachea must pass through 
the pharynx^ and to get into the pharynx it must pass 
through eitlier the mouth or nose. Nature intended that 
the nose should be the air passage, but many people 
breathe through the mouth because of some temporary 
or permanent obstruction in the nose. The nose is made 
especially for breathing ; it is provided with a moist 
mucous membrane for catching the dust ; it is full of 
blood vessels for warming the air. To assist in catching 
the dust, there are, near the opening of the nose, hairs 
kept moist by secretions. The passage through the nose 
is not simply a cylindrical canal, but very irregular, w4th 
folds which increase the surface, and not only aid in 
warming the air and removing the dust, but also aid 
the sense of smell by increasing the amount of surface 
exposed to odors. 

The larynx contains the vocal cords^ and is the organ 
for producing the voice, and so is sometimes called the 
voice box. One can feel the little point of his larynx, 
and by passing the fingers along the throat below the 
larynx he can feel the large, stiff tube whose walls con- 
tain little rings of cartilage. The object of these rings is 
to keep the trachea open. If it were not for these the 
trachea would collapse, and the breath would be shut off. 

Notice that down in the thorax between the two lungs 
the trachea branches into two parts, each looking quite 
like the trachea, only smaller (Fig. 40). These two 
parts are hronchi. Each bronchus subdivides within the 
lung into a series of treelike branches, until finally every 
portion of the lung substance is reached by minute ter- 
minal twigs of this system of branches. The divisions of 



RESPIRATION 



169 



the bronchi are called bronchial tubes. The bronchial 
tubes end in clusters of air cells^ which are similar to 
bunches of grapes. In the figure only a few of these 
clusters are shown, but the lung is made up largely of 
innumerable clusters lying side by side. 

The air passages consist, then, of nose, pharynx, larynx, 
trachea, bronchi, bronchioles, and air cells. All of the air 
passages are lined ivith mucous membrane. The mucous 
membrane of trachea, bronchi, and bronchioles is provided 
with ciliated cells. These cilia are always moving with an 




Fig. 40. — Air passages in the human lungs, a, larynx; 6, trachea; 
c, d, hronchi ; e, bronchial tubes ; /, cluster of air cells. 



upward, whiplike motion, which carries particles of dust 
and mucus up the trachea until it reaches the larynx, 
where it causes a tickling sensation and is coughed up. 

The branches of the pulmonary artery pass into the 
lungs by the side of the bronchi, and subdivide wherever 
the bronchi subdivide, being finally distributed in small 
branches to each cluster of air cells. The end branches 
of the pulmonary artery send to each cluster one or more 



170 PHYSIOLOGY 

arterioles, which break up into a network of capillaries 
similar to that shown in Figure 35, so that each air cell is 
surrounded by a network of capillaries. 

We must not forget that the pulmonary artery carries 
impure blood to the lungs for purification, so that the 
arrows in Figure 36 will need to be reversed, the impure 
blood passing in from the arterioles and becoming purified 
as it passes through the capillary system, and then, pass- 
ing out into the pulmonary veins, finally collects into four 
pulmonary veins which empty into the left auricle. 

The blood which circulates in the lung capillaries is 
separated from the air by the delicate mucous membrane 
of the air cell, the capillary wall, and a film of plasma ; 
yet we shall find that there is ample opportunity for the 
blood to be purified. 

3. THE MOVEMENTS OF RESPIRATION 

The diaphragm has already been mentioned as the 
most important muscle of the respiratory system. Refer- 
ence to Figure 39 will show the diaphragm arching upward, 
filling the space in the middle of the thorax and passing 
up to the heart. The lower lobes of the lungs fill the 
space between the high dome of the diaphragm and 
the wall of the thorax. Just below the diaphragm lie the 
stomach and liver, not shown in the figure. 

The muscular fibers of the diaphragm radiate outward 
from its center and are attached around the thoracic wall. 
The contraction of the diaphragm is brought about by 
all these fibers contracting at the same time. It must be 
easily seen that when the diaphragm contracts its dome 
will be flattened. Now the diaphragm is the partition 
wall between the thorax and the abdomen. The flatten- 
ing of the diaphragm is really a moving of all the dia- 



RESPIRATION 171 

phragm except its margins from the thorax toward the 
abdomen. That would tend to make more room in the 
thorax, and also to push the stomach and liver doAvnward 
further into the abdominal cavity. 

What would happen in the abdominal cavity is very 
easily understood. The stomach and liver push upon the 
intestine and all of these organs are pressed outward in 
every direction, and so distend the walls of the abdomen. 

It may not be so easy to understand just what takes 
place within the thorax. We know that when we draw 
up the piston of a syringe the air or water will rush 
through the nozzle of the syringe and fill up the space 
that would be left, so that there is really no vacant space 
in the syringe, that is, no vacuum. 

In a similar way, when the diaphragm pulls dow^nward 
toward the abdominal cavity it would tend to leave a 
vacuum around the lungs and heart, but the air rushes 
in at the nose and through the air passages, filling the 
lungs and allowing them to expand and fill up all of the 
space made by the contraction of the diaphragm. 

The diaphragm is not the only muscle of respiration ; 
the diaphragm makes only one wall of the thorax, a 
partition wall between the thorax and another body 
cavity. The outside walls of the thorax are also mov- 
able, though in a much smaller degree than is the case 
with the diaphragm. The curving ribs slant downward 
and forward from the backbone, and are so attached to 
the backbone that when the front ends are raised, the 
front wall of the chest, as well as the side walls, will be 
thrown out, thus increasing the space within the thorax, 
which the lungs swell out and fill (Fig. 41). The mus- 
cles which do this are the muscles which pass from the 
backbone to the collar bone and upper ribs, also the inter- 



172 PHYSIOLOGY 

costal muscles, which attach each rib to the next rib 
below it. 

The filling of the lungs is called inspiration. The lungs 
are alternately filled and emptied. The emptying of the 
lungs is called exjnration. When the lungs are to be 




Fig. 41. — Diagram illustratiDg the increase in the diameter of the thorax 
when the ribs are raised. 

emptied the diaphragm relaxes, and the muscles which 
have raised the ribs relax, the chest walls fall back to 
their position of rest; the abdominal walls, which have 
been distended by the pressure of the organs within come 
back to their position of rest, which pushes the diaphragm 
up into the thorax again, thus restoring to its position 
of rest all the muscles of respiration, and the ribs as well as 
the lungs.* As the walls of the thorax pass inward toward 
the lungs, they contract, and the air flows out of the nose. 



4. THE MOVEMENTS OF RESPIKATION {continued) 
I. FORCED BREATHING 

The breathing described in the preceding lesson is 
what is called quiet breathing. This is the way one 
breathes when he is sitting quietly or when asleep. The 
air which flows out and in the lungs in quiet breathing is 
called tidal air^ and amounts to about 30 cubic inches, 
or a little over a pint, for the average-sized adult man. 



RESPIRATION 173 

If one will observe his respiration when he is breathing 
quietly he will get a good idea of how much air flows 
out of and into the lungs, and how much movement of 
the chest and abdomen there is in quiet breathing. At 
the end of a quiet inspiration one is able to continue to 
draw air into the lungs. He can go on expanding his 
chest and abdomen until he reaches the limit of his 
capacity, drawing in about 100 cubic inches more of 
air. This extra air which one is able to draw into the 
lungs in a forced inspiration is called complemental air. 
In forced inspiration, all of the muscles of quiet inspira- 
tion are in use, contracting much more strongly than in 
quiet breathing, and besides these, muscles of the back 
and shoulders assist in raising the ribs and sternum. 

If, at the end of a forced inspiration, one begins to let 
the air flow out of the lungs, the 100 cubic inches of com- 
plemental air will flow oat first, followed by the 30 cubic 
inches of tidal air. After these 130 cubic inches have es- 
caped from the air passages and the muscles of respiration 
are in position of perfect rest, one may still force air out 
of the lungs. This is called /or c^(i exphation^ and is ac- 
complished mostly by the contraction of the walls of the * 
abdomen. This forces the intestines, stomach, and liver 
backward and upward against the diaphragm, thus forc- 
ing the diaphragm farther up into the chest cavity and 
forcing air out of the lungs. This air of the forced ex- 
piration is called reserve air^ and amounts to about 100 
cubic inches, but there is still remaining in the lungs air 
which one cannot force out voluntarily. This air that 
always remains in the lungs is called residual air,, and 
amounts to about 100 cubic inches. Though this residual 
air cannot be voluntarily forced out, it is sometimes forced 
out accidentally. If one falls upon his shoulders, or if 



174 



PHYSIOLOGY 



cu, m. 



through any accident the chest is suddenly compressed at 
the end of an expiration, a portion of the residual air may 
be forced out. In sucli a case one feels distressed and 
has difficulty in regaining the breath. 

Figure 42 shows the relative amounts of tidal, com- 

plemental, reserve, and residual 
air. It will be seen from the 
diagram that the amount of air 
which one can expel from the lungs 
after forced inspiration would 
equal about 230 cubic inches. This 
is called the lung capacity and is 
the average amount for an adult 
man 5 feet 8 inches in height. 
For each added inch in height 
the lung capacity would increase 
about 9 cubic inches ; and for 
persons shorter than the average 
the lung capacity would decrease 
9 cubic inches for each inch of 
height below the average. The 
average boy of fourteen would 
have a lung capacit}^ of about 120 
cubic inches ; the girl of four- 
teen should have about the same 
lung capacity as a boy of that 
age, but the average woman has 
a smaller lung capacity than the 
average man. 




Fig. 42. — Diagram showing 
the relative amounts of 
tidal, complemental, reserve, 
and residual air. Note that 
the brace shows the average 
lung capacity for the adult 
man. 



II. CHEST AND ABDOMINAL BREATHING 

It is frequently said that w^omen breathe differently 
from men, the chest movement being more pronounced in 



RESPIRATION 175 

a woman and the abdominal movement in a man. The best 
authorities agree now that there should be no difference 
in the breathing of men and women ; if there is a differ- 
ence it is because of the unhygienic clothing so frequently 
worn by women. 

5. BREATHING AND THE VOICE 
I. HOW THE BREATHING IS CONTROLLED 

The movements of the diaphragm are controlled by 
the phrenic nerves^ which can be traced upward from the 
thorax and the deep muscles of the neck into^ the spinal 
cord and up to the medulla oblongata, situated at the base 
of the brain. 

The intercostal muscles are controlled by the inter- 
costal nerves, each one of which passes directly into the 
spinal cord and upward to the medulla. These are the 
nerves which control the muscles of inspiration. The 
lower intercostal muscles which control the muscles of 
the abdominal walls are expiration nerves. 

The sensory nerves of the nose and those branches of 
the vagus nerve which supply the larynx and the mu- 
cous membrane of the lungs, are the sensory nerves of 
respiration. 

II. MODIFICATIONS OF BREATHING 

If mucus or any foreign body gets into the larynx it 
irritates the sensory nerves, a message is sent to the 
breathing center in the medulla, from which a message is 
sent to the abdominal muscles, Avhich contract quickly, 
causing a coughing^ which dislodges and throws out the 
offending substance. 



176 PHYSIOLOGY 

When the membrane of the nose is irritated in any way, 
a similar explosion of the air through the nose will gen- 
erally remove the irritating matter. This act is called 
sneezing. 

Yawning is a deep inspiration in which the lungs are 
well filled and inflated, furnishing an extra supply of 
oxygen for the system. 

Hiccoughing consists of a sudden contraction of the dia- 
phragm, which causes a spasmodic inspiration ; this is 
blocked by the sudden closure of the larynx, causing a 
''hiccough." 

Sighing is similar to yawning but is caused by such 
emotions as grief or sorrow. 

Crying and Laughing, These are combined modifica- 
tions of breathing and the voice. They are caused by the 
emotions, and consist of a deep inspiration, usually fol- 
lowed by a series of spasmodic expirations which are 
vocalized or in which the voice is acting. 

Sohhing is a convulsive inspiration, also emotional, and 
usually follows prolonged crying. 

III. THE VOICE 

In describing the organs of respiration the larynx or 
voice box was mentioned. In the upper part of the 
larynx two membranes pass out from the sides toward the 
middle. The edges of these membranes are rounded 
cords which are so attached to the walls of the larynx 
that they may be brought close together and stretched 
tightly through the contraction of the muscles in the walls 
of the larynx. These cords are the vocal cords. When 
the vocal cords are tightened and brought near together, 
the air passing over them sets them to vibrating. This 



RESPIKATION 177 

vibration causes a sound which we call the voice, INIost of 
the higher animals have a voice. Animals that have a 
voice use it in the expression of their emotions and desires 
first of all. A child first uses its voice for this purpose. 
When it begins to talk it expresses other ideas. 

Man has cultivated his voice along with his mind, so 
that he is able to express, not only the emotions and 
desires, but a continuous train of thought in a succes- 
sion of sounds which we call speech. These sounds are 
grouped into syllables and words; each syllable contains 
at least one vocal or vowel sound which is made by the 
larynx and which is more or less modified by the organs 
of articulation. These modifications of the vocal sounds 
are termed consonants, and they are produced by the vari- 
ous positions of the lips, tongue, teeth, and palate during 
the formation of the sound by the larynx. 

In the word or syllable hat^ the larynx makes the vocal 
or vowel sound a, and this vowel sound is introduced by 
the lip consonant (labial) 5, and foUow^ed by the tongue- 
palate consonant (palato-lingual) t. 

The vowels of the English language are a, g, 2, o, and u^ 
which may be modified in quality by the vocal organs to 
make about seventeen different sounds. 

*The consonants, about twenty-one in number, are sub- 
divided into the labial or lip consonants, ^, 5, tv ; the 
labio-dental or lip-teeth sounds, /, v ; the linguo-dental or 
tongue-teeth sounds, th ; the nasals, m, ti, ng ; and the 
palato-linguals or palate-tongue sounds. 

People of culture and refinement usually possess voices 
which are under perfect control under all circumstances, 
never pitched too high or too low ; when they speak 
their voices are well modulated and their words are dis- 
tinctly enunciated. 



178 PHYSIOLOGY 

6. IIOAY THE AIR IS CHANGED IN THE LUNGS 
I. THE COMPOSITION OF THE AIR 

Air is a mixture of gases. The mixture is composed 
chiefly of nitrogen (about four fifths), oxygen (about one 
fifth), with a very small amount of carhon dioxide. ThSre 
are minute portians of other gases, because other gases 
than those mentioned above are escaping into the atmos- 
phere as the result of various natural phenomena; some sul- 
phurous and other gases may escape from volcanoes, and 
what is called marsh gas escapes from decaying vegetable 
matter in swamps. There escape into the atmosphere 
which is over great cities and manufacturing centers, large 
quantities of various gases, among them illuminating gas, 
and sulphurous gases from the combustion of low grades 
of coal, also quantities of carbon monoxide gas and of 
ammonia gas. But when one remembers that the atmos- 
phere is at least forty miles deep over the whole earth, and 
that it is being constantly stirred up by the winds, and 
that the noxious gases are gradually dissolved in the sur- 
face waters of the earth, and that the carbon dioxide gas 
is being consumed by the plants for food, it must be clearly 
seen that the proportion of these noxious gases in the 
general atmosphere is too slight to take into consideration. 

Besides all of the gases which go to make up the atmos- 
phere, there is the water of the atmosphere, which is a 
most important constituent, but which is not usually in- 
cluded among its gases. Most of the water of the atmos- 
phere is in the form of an invisible vapor which the 
atmosphere takes up from the surface water of the earth. 
Warm air takes up more than cold air. In your physical 
geography you will learn that when warm air which is 



RESPIRATION 179 

saturated with invisible moisture is cooled, tlie moisture 
collects in minute drops which gather in a visible cloud. 
When one breathes into the cold winter air he can see 
the cloud of vapor passing from his nostrils. This vapor 
is invisible while it is in the air passages, and becomes visi- 
ble only when it passes out into the cold air, where the 
moisture is collected into drops. The clouds that float 
through the air are masses of visible vapor. The moisture 
of the atmosphere is very important to consider in the 
hygiene of the lungs. 

The nitrogen of the atmosphere is colorless, tasteless, 
odorless, and is one of the most inactive gases known to 
chemists ; the oxygen of the air is also colorless, odorless, 
and tasteless, but is the most active gas known to chemists, 
and is the most universal in its combination with other 
elements, so that it enters into the composition of the 
w^ater which covers so large a part of the earth's surface 
and, practically, every rock in the earth's crust, and forms 
a large part of every plant and animal living upon the 
earth. Our studies in the physiology of plant and animal 
nutrition teach us that it is through the combination of 
oxygen with the tissue elements that all plant and animal 
energy is liberated or generated. 

II. THE CHANGES WHICH THE ATMOSPHERE UNDERGOES 
IN THE LUNGS 

We take air into the lupgs for its oxygen. When air 
is drawn into the lungs but once and exhaled in a normal 
way, it loses about one fourth of its oxygen. If the air 
lost the same amount when rebreathed, all of the oxygen 
would be consumed if the same air were breathed four 
times. But when the air is rebreathed, only one fourth of 



180 PHYSIOLOGY 

the remaining oxygen is absorbed ; thus less and less is taken 
at each rebreathing of the air. And if one were shut into 
a very small space, he would take out one fourth of the 
oxygen in breathing the air the first time, and about one 
fourth of the remainder the second time, and so on, always 
taking one fourth of the remainder at each successive 
rebreathing of the air, until finally nearly all the oxygen 
would be exhausted. The death of the individual would 
soon follow, of course. 

Besides the change in the oxygen, carbon dioxide is 
added to the air. A little smaller quantity of the carbon 
dioxide is added than enough to make up for the oxygen 
which is taken away, so that the air exhaled is a little 
less in quantity than the air inhaled when measured 
under the same conditions. 

If the inspired air is dry it will take up moisture from the 
air passages ; and so carry away a certain amount of water 
from the sj^stem. It will always carry away water from 
the system unless it has the same temperature as the air 
passages, and is saturated wdth water at that temperature. 

Besides the subtraction of oxygen and the addition of 
carbon dioxide and water, there is a change of tempera- 
ture, the exhaled air being warmed to nearly the tempera- 
ture of the blood, and there is also an addition of a small 
amount of organic matter carried away from the air 
passages. 

7. HOW THE BLOOD IS CHANGED IX THE LUXGS 
I. HOW THE BLOOD IS OXYGENATED 

It has been stated in a previous lesson that the work of 
the red blood corpuscles was to carry oxygen from the 
lungs to the tissues. The first question which arises is, 



RESPIRATION 



181 



how does the oxygen get from the air cells of the lungs to 
the red blood corpuscles ? When a gas is in contact with 
the surface of a liquid, directly or through a moist mem- 
brane, the gas will pass into the liquid direct or through 
the membrane, j^apidly at first, and more slowly later, 
until there is no more absorption of the gas, when we say 
the liquid is saturated. If the liquid is flowing past the 
membrane, the process of absorption of the gas will go on 
:at the same rate, because the liquid is continually renewed. 
Between the air in the air cell and the red blood cor- 
puscles in the capillaries of the lungs there intervene 
(1) the thin membranous wall of the air cell, (2) a thin 
submucous coat whose 
spaces are filled with 
lymph, (3) the wall of 
!~the "capillary, (4) the 
.plasma within the capil- 
lary. Then comes the red 
blood corpuscle (Fig. 
43, a). 

' Every space between 
fibers and cells is filled 
with plasma or lymph 
:and the cells themselves 

Bronchiole 

•are composed largely of fig. 43. -Diagram of two air cells, show- 
water, so that the OXyg-en ^°^ ^^® capillary network which covers 
, them, and at a the structures which 
readily passes through intervene hetween the air and the blood 
the membranes and flu- ^^^ indicated: l, mucous membrane of 

the air cell ; 2, submucous meshwork ; 

ids just mentioned, and 3, wall of capillary; 4, plasma in capil- 

finally reaches the red lary; 5, red blood corpuscle, 
blood corpuscle which is floating along in the capillary. 

Now red blood corpuscles have a strong affinity or 
appetite for oxygen, and immediately take up from the 




182 PHYSIOLOGY 

plasma the oxygen which comes in, and pass on, leaving 
the plasma as poor in oxj'gen as it was to start with ; so 
that more oxygen readily passes into the capillary, and 
finds the plasma and corpuscles ready to take it up at 
once and carry it off to the tissues. 

II. HO\V THE BLOOD IS FREED OF CAKBOX DIOXIDE 

The blood leaves the tissue with a heavj^ load of carbon 
dioxide, which is carried away from the tissues to be 
thrown out of the system. This carbon dioxide is carried 
partly by the red blood corpuscles and partly by the 
plasma of the blood. 

If a pint of venous blood were to be put under an air 
pump, and a vacuum made over it, carbon dioxide would 
pass off from it, and if this were measured at standard 
atmospheric pressure and at zero degrees, there would be 
forty-five or forty-six per cent as great volume of gas as 
there was volume of blood. 

If arterial blood were tried in the same wa}', a volume 
of carbon dioxide equal to about fortj^ per cent of the 
volume of the blood could be drawn off. 

From this it seems that the blood always has carbon 
dioxide in it, carrying a big load from the tissues to the 
lungs and a somewhat smaller load from the lungs back 
to the tissues, so that it gives up only about one ninth of 
this load in the lungs. 

Whether this carbon dioxide gas is given up from the 
corpuscles or from the plasma is not known, and part is 
probably given from each. The reason the carbon dioxide 
gas leaves the blood and passes into the air cells of the lungs 
is because there is very little carbon dioxide gas in the air 
cells of the lungs and a great deal in the blood, and so it 



RESPIRATION 183 

naturally diffuses toward the lungs ; and during the time 
the venous blood is passing through the capillaries, one 
ninth of the carbon dioxide will have time to diffuse into 
the air cells, while the red blood corpuscles are taking 
their load of oxygen for the tissues. 

8. TISSUE RESPIRATION AND BODY HEAT 

The real object of the w^hole process of respiration is to 
furnish oxygen to the tissues and to carry away from the 
tissues the carbon dioxide. Each cell is neither able to 
build up its own protoplasm nor to do its special work with- 
out oxygen. When the supply of oxygen stops, all work 
stof)s. The active tissues always want oxygen, though 
they may want more oxygen at one time than at another. 
The harder they work, the more oxygen they want; when 
one is doing hard, muscular work, or exercising vigorously, 
the muscles all over the body call for more oxygen. They 
make this call through the help of the sympathetic ner- 
vous system. This causes the respiratory muscles to act 
more vigorously, so that the breathing is deeper and more 
rapid, more oxygen is brought into the lungs, more is 
taken up by the blood. 

At the same time that the lungs are working harder, 
the heart is working harder, thus making a more rapid 
stream of blood through the lungs, and this takes up the 
oxygen more rapidly, so that the amount of oxygen 
carried in any particular quantity of blood during exercise 
need not be greater than that carried by the same quantity 
of blood during rest. 

The affinity or appetite of the tissues for oxygen is 
always stronger than that of the red corpuscles, so that 
when a corpuscle comes to the capillaries and moves 

hall's PHYS. 12 



184 PHYSIOLOGY 

slowly along them between active tissue cells on either 
side which are calling for its load of oxygen, it has to 
part Avitli tliis load and return by way of the veins to the 
lungs for another load of oxygen. Active muscle, gland, 
and nerve cells are constantly giving off carbon dioxide 
into the tissue plasma which surrounds the cells. The 
blood in the capillaries has less carbon dioxide than that 
outside of the capillaries in the tissue, so that carbon 
dioxide diffuses from the tissue plasma into the blood 
plasma, and thus loads the blood with carbon dioxide, 
which is carried by way of the veins to the lungs, and 
tliere given up in the way described above. 

I. BODY HEAT 

Aristotle believed that the heat of the body was made 
within the heart by a combination of the " vital spirits " 
w^th the blood. For over two thousand years it was be- 
lieved that the heat of the body was generated in the blood. 

Lavoisier, who discovered oxygen and the principles of 
oxidation, believed that heat was generated in the blood 
of the lungs where the oxygen first entered it. After his 
time, and until recently, the heat was believed to be 
generated within the capillaries of the active tissues ; but 
since the importance of the cell has become understood, it 
is generally believed that nearly all, if not quite all, of 
the oxidation of the substances of the body takes place 
within the living cells, so that the active tissue cells, 
whose substance is being oxidized, are the heat generators. 

The muscle tissue comprises four fifths of the active 
tissue of the body. Muscle tissue is always generating 
heat energy, and some of the time it is generating both 
heat and motion. As the blood circulates through the 



RESPIRATION 185 

muscles it becomes heated, and then flowing to other 
parts of the body it distributes this heat so that all parts 
of the body are kept warm, the deeper tissues of the 
body being kept warmer than those near the surface. 
The temperature of the body is regulated partly by the 
regulation of the rate of heat generation and partly by the 
regulation of heat radiation from the body. The body is 
giving up heat to the cooler atmosphere all the while. As 
much as three fourths of all the energy of our food is re- 
quired to keep the body warm ; the rest is devoted to 
body building and to the movements and other activi- 
ties. If one goes out into the cold winter air, the blood 
at first withdraws to the deeper tissues, then is sent to the 
muscles, where an extra supply of heat is being generated, 
and after being warmed in the muscles, passes to the skin 
to warm the surface of the body. If the body becomes 
too warm, the blood will go to the skin, and the sweat 
glands of the skin will pour out perspiration upon the 
surface, and so the body will be quickly cooled. 

Thus we see that these two things working together, 
heat generation and heat radiation, keep the body contin- 
ually at nearly the same temperature. 

II. FEVERS 

If the heat generation goes on too rapidly, or if the 
heat radiation goes on too slowly, as it would if the skin 
were too dry, the temperature of the body will rise, and 
we say the person has a fever. In the treatment of fevers 
the physician usually tries either to decrease the heat 
generation in the body, or to increase the heat radiation, 
and thus reduce the temperature of the body to the 
normal one. 



186 PHYSIOLOGY 

9. HYGIENE OF RESPIRATION 
I. RESPIRATORY MOVEMENTS 

The clothing of the chest and abdomen should be loose 
enough to enable free movements in respiration. It is 
probable that one of the most frequent causes of ill liealth 
in women is the improper oxidation of tissue as a result 

(1) of shallow breathing due to impro23er clothing, and 

(2) of living much within doors in ill-ventilated houses. 
No one should allow a day to pass without filhng the lungs 
several times to their greatest capacity. The advantage 
of these deep inspirations is increased if the lungs are filled 
with pure, out-of-door air. It is still further increased if 
the respirations are deep as a result of vigorous exercise out 
of doors. If one must be confined to the house for most 
of the time, it is advisable to devote a few minutes two or 
three times each day to vigorous calisthenics, accompanied 
by deep breathing, preferably in front of an open window. 
The air should always pass through the nose, as that is 
nature's respiratory passage, and is so constructed as to 
free the air from dust and to Avarm it before it goes into 
the air passages. 

II. IMPURE AIR 

The principal impurity of the air in buildings is carbon 
dioxide given off from the lungs of the people in the build- 
ing. It is also given off in large quantities by lamps and 
gas stoves, and may be given off in small quantities from 
coal stoves. Another impurity is the dust always found 
in buildings. Occasionally there may be noxious gases 
given off from furnaces, or escaping from gas fixtures or 
from the plumbing. The latter is called sewer gas. 



RESPIRATION 187 

The greatest care should be taken by those who have 
buildings in charge to insure their absolute freedom from 
all of these harmful, and sometimes fatal, impurities of 
the air. Decaying vegetables and stagnant water in 
cellars are frequently causes of disease, contaminating 
especially the atmosphere of the building. No such 
known cause of disease should be tolerated in a building. 

III. ventilatio:n^ 

Ventilation is a term used to designate the change of 
air in a building. Every properly constructed building is 
planned to have an air space for each occupant so large 
that the air will not have to be rapidly changed in order 
to be sufficiently pure. 

The amount of space allowed for each person occupying 
a schoolroom during only a few hours in a day is 250 cubic 
feet. In a room in a dwelling used all day or all night, 
300 cubic feet should be allowed, while in a ward in a 
hospital it is usual to allow 1000 cubic feet for each 
occupant. 

When a room is properly ventilated, the air should 
seem odorless to one coming in from out of doors. A 
proper system of ventilation provides for a constant 
change of air without noticeable drafts. An occasional 
throwing open of doors and windows for a general rush- 
ing in of out-of-door air, and a cooling of the air down 
several degrees, is an exceedingly clumsy way of venti- 
lating a room. The opening of one window of a room 
may not permit a sufficient exchange of the air within 
with that outside, and it is difficult at best to ventilate 
a house through the windows alone without causing 
drafts. 



188 PHYSIOLOGY 

Public buildings are usually ventilated through flues 
in the walls, flues opening near the floor and near the 
ceiling in each room. An important feature of the ven- 
tilation of a dwelling house is the fireplace, with its flue. 
When the fireplace is open, as it should always be, the 
dropping of several windows, upstairs and down, an inch 
at the top will usually afford ample ventilation, without 
any noticeable drafts. 

The presence of illuminating gas, or other gas having a 
distinct odor, may be at once detected ; the most danger- 
ous gas in a building is sewer gas, which has no odor. If 
sewer gas is present, it is usually suspected by the family 
physician from the general health of the members of 
the household, and if an expert examination reveals its 
presence, the plumbing of the house must be repaired. 
Fortunately, the escape of sewer gas into a house is not a 
very frequent occurrence. 

The gas that is always present, and always injurious 
when present in an amount to exceed eight parts in ten 
thousand, is carbon dioxide. As carbon dioxide is odor- 
less, it is necessary to have some simple test to show when 
it is present in excess of this proportion named above. 

Keep on hand a bottle of clear limewater. To test the 
air in any room to see if it is sufficiently free from carbon 
dioxide to be wholesome, go into the room, provided with 
a pint fruit jar full of water, with the bottle of limewater, 
and with a teaspoon. Pour out the water from the fruit 
jar, and its place will be taken by the air of the room. 
Then pour into the fruit jar six teaspoonfuls of the lime- 
water, fasten on the cover of the fruit jar tightly, and 
shake it vigorously. If there are more than eight parts 
in ten thousand of carbonic acid present in the room, the 
limewater will show it by turning a milky color. If there 



RESPIRATION 189 

is a smaller proportion than that, the limewater will not 
be noticeably affected. 

10. EXPERIMENTS 

Get about a pound of unslacked lime from a mason or 
plasterer. Put half of it into a quart fruit jar and fill the 
jar with water. The lime will slack in the jar, and a por- 
tion of the lime will combine with the water to make 
calcium hydrate, or limeivater. After one or two days 
the lime w411 have settled to the bottom and there will be 
clear water on top. Pour the clear portion off carefully 
into another jar or bottle and label it : Calcium Hydrate or 
Limewater. 

1. Fill a drinking glass half full of limewater, then 
take a glass or rubber tube or lemonade straw and blow 
gently through the tube into the limewater, completely 
emptying the lungs of air, thus making the air which was 
in the lungs bubble up through the limewater. Notice 
the white cloud which gathers in the previously clear 
limewater. 

This white cloud is a precipitate of calcium carbonate 
which was formed by the carbon dioxide of the breath 
combining with the calcium of the limewater. This cal- 
cium carbonate is the same material of which your chalk 
crayons are made, and the same material of which marble 
is composed. 

2. Put a piece of candle about an inch long into an 
empty drinking glass and light it. The flame is at first 
fed by the oxygen in the glass, but as soon as the oxygen 
is used up the flame dies. Take out the candle, relight 
it, and lower it into the glass ; it will go out as soon as it 
gets below the surface of the carbon dioxide which now 



190 PHYSIOLOGY 

fills the glass. Put a sheet of wet paper over the glass to 
keep the carbon dioxide from mixing with the air. Into 
another glass of the same size put two tablespoonfuls of 
limewater. Invert the glass containing the carbon dioxide 
over the glass containing the limewater; draw out the 
sheet of paper from between the glasses, and vigorously 
shake the two glasses, holding them together at the rim. 
The carbon dioxide has mixed with the limewater and 
formed the turbid cloud of calcium carbonate. 

From these two experiments we find, first, that by the 
oxidation of a candle, as well as by the oxidation of the 
tissues of the body, carbon dioxide is formed. Second, 
we find that the flame of a candle Avill be extinguished in 
an atmosphere of carbon dioxide. It is also true that the 
" flame of life " will be extinguished in a similar atmos- 
phere. 

3. Test the air in your schoolroom with a fruit jar as 
directed above in the text, to see if the ventilation is 
sufficient. If it is not sufficient, try to devise some means 
by which the ventilation can be improved without causing 
direct drafts upon the occupants of the room. 

PROBLEMS 

1. How many pupils should be seated in a schoolroom 
30 feet wide, 40 feet long, and 15 feet high ? 

2. If a schoolroom is 20 feet wide and 30 feet long, 
how high should the ceiling be to accommodate 30 
pupils ? 

3. How many individuals may occupy a sleeping room 
10 by 15 feet, 8 feet high? 

4. How high should a hospital ward be which is 20 
feet wide, 40 feet long, to accommodate 10 patients ? 



RESPIRATION 191 

11. THE EFFECTS OF NARCOTICS UPON RESPIRATION 

I. EFFECTS OF ALCOHOL UPON THE RED BLOOD COR- 
PUSCLES 

Alcohol acts upon the red blood corpuscles, lessening 
their power to take oxygen from the air cells of the lungs 
and carry it to the tissues of the body.^ 

The direct effect of the above upon the tissues is, 
according to Dr. Parker of Chicago, the diminishing of 
the functional activity of the secreting and excreting 
structures, causing the blood to accumulate and retain 
the waste material. 

n. RELATION OF ALCOHOL TO ANIMAL HEAT 

Dr. Bodlander proved several years ago that about ninety 
per cent of alcohol taken into the stomach is oxidized, 
forming carbon dioxide gas and water, and generating 
heat. He believed that the injury done by alcohol con- 
sists in part of the robbing of the other cells of the body 
of their supply of oxygen, and the rapid formation of 
carbon dioxide, which acts as a poison until thrown out 
of the system. 

'' For the heating of the body it seems that only certain 
kinds of carbonaceous substances are suitable. Tlie action 
of alcohol upon the cells tends to cause their degeneration, 
changing them to fat, and, as it were, makes the cells of 
the various organs grow prematurely old. Alcohol is, 
it seems, a most unsuitable substance with which to pro- 
duce warmth." 2 

1 AHbutt's Sijstem of Medicine, Vol. Ill, p. 839. 

^ Medical Pioneer, October, 1896, p. 204, quoting from Pfluger's Archives, 
Vol. XXXII, p. 399. 



192 PHYSIOLOGY 

Men who use ardent spirits often say that they do so 
in winter to ^'keep their bodies Avarm." No one could 
make a greater mistake than to suppose that the effect of 
alcoholic drinks is to warm the body. Many and often 
repeated experiments upon this question prove that when 
the liquor is taken in sufficient quantity to make the 
person feel warm he is really losing body heat through 
the skin, and the temperature of the body is falling. If a 
person is exposed to extreme cold for several hours, the 
temperature of the body may fall so low as to endanger 
life.i 

We learn from this that the body is not always warm 
when it feels warm. In the case above mentioned the 
person feels warm because the skin is kept warm by the 
blood flowing to it in unusual amounts. 

III. RELATION OF ALCOHOL TO LUNG DISEASES 

A recent article in the Medical Times^ quoting from 
the Hospital G-azette^ states that the use of alcohol makes 
a person more liable to pneumonia. 

Dr. Delearde says that pneumonia is much more severe 
in those addicted to the use of alcoholic drinks than in 
others ; that it runs a longer course ; that it is often ac- 
companied by violent delirium, followed by prostration, 

1 Professor Brunton, St. Bartholomew Hospital, London. Lectures on the 
Action of Medicine, p. 128. "A party of engineers were surveying in the 
Sierra Nevadas. They camped at a great height above the sea level, where 
the air was very cold and they were chilled and uncomfortable. Some of them 
drank a little whisky and felt less uncomfortable ; some of them drank a lot 
of whisky and went to bed feeling very jolly and comfortable indeed. But in 
the morning the men who had not taken any whisky got up in good condition ; 
those who had taken a little whisky got up feeling very miserable ; the men 
who had taken a lot of whisky did not get up at all ; they were simply frozen 
to death. They had warmed the surface of their bodies at the expense of their 
internal organs." 



RESPIRATION 193 

or even unconsciousness, and that in those who recover at 
all, there frequently occur abscesses in the liver or in other 
organs. 

Dr. Legendre, a Paris physician, has recently published, 
for public distribution, a leaflet in which he says : " Alco- 
hol is a frequent cause of consumption by its power of 
weakening the lungs. Every year we see patients who 
attend the hospital for alcoholism come back after a 
period to be treated for consumption."^ 

An American medical writer ^ points out the reason why 
the use of alcohol makes one liable to consumption. He 
mentions the use of alcohol among various other things 
which cause the natural vital resistance of the healthy 
body to be impaired. Among those other things men- 
tioned with alcohol, which produce this impairment of 
vital resistance, are : '^ Living in overcrowded, ill- ven- 
tilated houses, on damp soils, or insufficient clothing and 
outdoor exercise." 

IV. INFLUENCE OF TOBACCO UPON THE RESPIRATORY 

SYSTEM 

'' Nicotine stimulates secretion in general, as is illus- 
trated by its influence upon the mucous glands of the 
mouth. This overstimulation of the mucous membrane 
would naturally lead to the development of catarrhal 
affections."^ 

REVIEW OF THE RESPIRATION 

1. Every living thing, both plant and animal, needs oxygen. The 
process of furnishing oxygen for the tissues of a plant or animal is 
called respiration. 

1 London Lancet. 

2 See Journal of American Medical Association, October 23, 1897, p. 847. 

3 Dr. J. W. Seaver, Yale University, in Journal of Inebriety. 



194 PHYSIOLOGY 

2. The Inspiration and Expiration oi air to and from the lungs are 
together called External Respiration ; while the exchange of oxygen 
for carbon dioxide in the tissues is called Internal Respiration. 

3. The .4 Ir passages are : the nasal passage, the pharynx, the larynx, 
the loindpipej the bronchi, the bronchioles, and the air cells. 

4. The Air passages, below the larynx, are lined luith ciliated cells. 
The cilia carry the mucus and particles of dust that may enter the 
lungs with the air up to the larynx, where it gives one a tickling sensa- 
tion and is coughed up. 

5. The Diaphragm is the principal muscle of respiration. The inter- 
costal muscles and the abdominal muscles assist. 

6. The movements of the chest and abdomen should not be interfered 
with by clothing that fits too tightly. 

7. Describe : Coughing, sneezing, yawning, hiccoughing, sighing, 
crying, laughing, and sobbing. 

8. How many vowels has the English language? How are these 
vowel sounds produced and how modified? How many consonant 
sounds in English? How are consonants classified and how are they 
produced? 

9. What are the characteristics of a cultured and refined voice? 
All people may cultivate refinement in the voice. One is judged more 
by the voice and the language than by anything else w^hen he first 
meets a stranger. First impressions are very valuable when favorable, 
and very damaging and difl[icult to remove when unfavorable. 

40. The air is composed chiefly of Nitrogen and Oxygen, with a 
little Carbon dioxide gas and Water vapor. 

14 . In the lungs the air gives up about one fourth of its oxygen, receives 
carbon dioxide in almost an equal quantity, and receives water vapor, 
and also a small amount of organic matter. 

42. Oxygen is carried by the red blood cells, while carbon dioxide is 
carried mostly by the plasma. 

43. The heat of the body is produced by the oxidation of its tissues. 

44. The heat of the body is regulated partly by changes in the rate of 
oxidation and partly by changes in the rate of the giving up of heat 
by the skin. In a similar way one changes the temperature of a 
house by changing the rate at which the fire in the furnace burns, or 
by opening or closing windows. Both of these methods of regulating 
may be changed at the same time. 

15. One should often breathe deeply to expand and develop the 



RESPIRATION 195 

lungs. One should breathe pure ah' either out of doors or in well- 
ventilated rooms. 

16. Alcohol, though oxidized in the bodi/, lowers the temperature, be- 
cause more heat is lost from the skin than is produced by the oxida- 
tion of the alcohol. Explain this. 

17. The use of alcohol weakens the lungs and makes one more liable to 
lung diseases than he tcould he if he abstained from it. 

18. The use of tobacco is likely to cause or to increase the tendency 
to catarrh. 



CHAPTER VIII. — HOW THE FOOD IS USED IN 

THE BODY 

The chapter on nutrition described foods, and told how 
they were digested in the alimentary canal, but did not 
tell how the foods were used by the body after they were 
digested. 

The object of this chapter is to show first, how the 
digested food is absorbed from the alimentary canal ; and 
second, how it is built up into living tissue in the body ; 
and third, under what conditions it is oxidized, and what 
is formed as a result of the oxidation. Before beginning 
these subjects, let us review the chapter on nutrition by 
answering the following questions : — 

1. How many and what kinds of food are there, or how 
many kinds of food stuffs ? 

2. What is the name of the digestive fluid secreted into 
the mouth? 

3. On what class of foods does this fluid act, and what 
changes does it produce ? 

4. What digestive fluid is secreted into the stomach ? 

5. On what kind of food does it act ? 

6. What change does it produce upon this food ? 

7. What digestive fluids are secreted into the small 
intestine ? 

8. What kinds of food are digested in the small intes- 
tine ? 

9. What name is given to the partly digested food that 
passes through the stomach into the small intestine ? 

196 



HOW THE FOOD IS USED IN THE BODY 197 

10. To what form are all the starches and sugars finally 
reduced by the digestive process ? 

11. To what form are all proteid foods reduced by the 
digestive process ? 

12. To what forms are the fats reduced by the digestive 
process ? 

1. HOW THE DIGESTED FOOD IS ABSORBED FROM 
THE ALIMENTARY CANAL 

After the digestive process has changed the starches 
and sugars to dextrose, the proteids to peptones, and the 
fats to soap and emulsion, the food is still no part of the 
body. It is inside of the body, but in a closed tube, and 
until it gets through the walls of the tube it is not part 
of the body. 

The interior lining of the intestines is thrown up in folds 
which, when magnified, look like fingers projecting into 
the intestines (Fig. 44). These are the villi which absorb 
the food into the system. If we magnify the villus very 
much, we see the whole surface is covered with absorb- 
ing cells. They are not open, but the chyme, or digested 
food, passes through the thin cell walls. If we cut a thin 
slice across the villus (Fig. 45), we see the absorbing cells 
leading toward the interior, where there are many blood 
vessels, and beyond which, in the very center of the 
villus, is a tube called a lacteal, which you know is an 
intestinal lymphatic. 

Some of the nourishment absorbed bj^ the cell is taken 
up by the blood vessels, and some goes into the lacteal 
wdiich carries it to a large duct, called the thoracic duct, 
which goes up the left side of the center of the body to 
the neck, where it empties into the jugular vein (Fig. 38, 



198 



PHYSIOLOGY 



p. 150). The lacteals take up the fats and part of the 

peptones. 

The rest of the nourishment, the sugars and a part of 

the peptones, is taken up by the blood vessels which unite 

to form the portal vein, 
and is carried by the 
blood to the liver. 

When the foods are 
passing through the 
absorbing cells of the 
villus, a change is 
made in some of them 
by the absorbing cells. 
The peptone absorbed 
from the alimentary 
canal is sent into the 
blood vessels, not as 
peptone, but as blood 
albumen, in which form 
it accumulates until it 
is taken up from the 
capillaries by the liv- 
ing tissues. The fats 
are taken up from the 
alimentary canal by 
the absorbing cells, 
and turned into the 
lacteals in minute glob- 
ules. These globules 
floating in the lymph 

plasma give it the milky appearance. The sugar absorbed 

is turned into the blood vessels unchanged, and so passes 

to the liver as sugar. 




Fig. 44. — Showing the villi or fingerlike pro- 
jections of the mucous membrane of the 
small intestine. In the third one from the 
right and second from left notice the central 
lacteal {i). The intestinal glands are shown 
at (A). The heavy black lines are blood 
vessels. [PiersoL] 



HOW THE FOOD IS USED IN THE BODY 



199 



2. HOW DIGESTED FOOD IS BUILT UP INTO LIVING 
TISSUE IN THE BODY 

In the previous lesson we traced the absorbed food 
stuffs directly into the blood of the portal vein or indi- 
rectly into the veins by way of the lacteals and the 
thoracic duct, so that the absorbed food at once becomes 




Fig. 45. — Showing a cross slice of a villus. Note the central lacteal {c.L), 
the blood capillaries (c), the absorbing cells all around the villus, the 
mucus-forming cells at (g). [Schaefer.] 

a part of the circulating fluids of the body ; but it does 
not become living tissue until it is absorbed into the liv- 
ing cells of the tissue. 

Let us first trace the dextrose. Sooner or later all the 
dextrose absorbed circulates through the liver. Figure 
46 shows the general shape of the liver as it looks from 
beloAV. You will notice that the portal vein divided, send- 
ing a branch to each lobe of the liver. Notice the liver 
artery which brings oxygenated blood from the lungs, so 
that there are two streams of blood passing to the liver, 
one from the intestines, and one from the lungs, while 
hall's phys. — 13 



200 PHYSIOLOGY 

there is one stream of blood going away from the liver by 
Avay of the vena cava. 

The gall bladder serves as a reservoir to collect a por- 
tion of tlie bile which is from time to time sent out through 
the bile duct into the intestines. Now if a very thin 
slice were made through the liver, and this slice examined 
under a high power microscope, one would find it divided 




Fig. 46. — Under surface of the liver. [Tracy.] 

into little five-sided or six-sided areas called lobules 
(Fig. 47). 

The blood of the portal vein passes through a network 
of veins marked p in the figure, forming a network of 
venules between the lobules. From this network of 
venules, innumerable fine capillaries pass toward the 
center of each lobule, gathering there into a venous trunk, 



HOW THE FOOD IS USED IN THE BODY 



201 



which passes out of the lobule and joins others on the 
way to the vena cava. 

While the blood is passing through the capillaries, an 
opportunity is given for the active gland cells of the 
liver (which are shown in two places in the lobules only, 
though really they fill all the space) to absorb the dextrose 
from the blood. What these cells do with the dextrose 




Fig. 47. — Diagram of two liver lobules. Note the branches of the portal vein 
(marked p) , from which a system of capillaries pass in to the middle of the 
lobules. In the lobule at the right is shown how the blood gets oat of 
the lobule and joins a branch of the liver vein on its way to the vena cava. 
Note the liver cells between the capillaries. The liver cells do the work of 
the liver. [Landois.] 



is one of the most wonderful processes ; they change it hack 
to starchy so that food that was taken in the form of starch 
is changed to sugar, and then back to starch in the body. 
This liver starch is called animal starch. 

The liver acts as a storehouse for this kind of food, so 
that after a meal where considerable starch or sugar has 
been eaten, the liver will be filled with starch, which is 
thus stored away to be given out a little at a time until 



202 PHYSIOLOGY 

the next meal. When this food is needed by the system, 
which will probably occur within two hours after it is 
stored in the liver, the liver changes the starch back to 
sugar, and the liver cells throw this sugar out into the 
capillaries again, and from the capillaries it passes into 
the liver vein, and from the liver vein into the vena cava, 
which carries it to the right side of the heart, whence it 
goes to the lungs, and is sent to the left ventricle. The 
left ventricle sends it through the arterial system to the 
tissues, where, as a part of the plasma, it oozes through the 
capillaries and around the cells of the tissues. 

Now these cells use more sugar than anything else. 
All the living cells of our body use sugar ; so the sugar is 
absorbed from the plasma and taken into the living cells, 
where it becomes a part of their protoplasm, that is, it is 
assimilated, but here it is soon oxidized to generate the 
energy which the cells must use in their work. 

The fat which was thrown into the venous system in 
the form of minute globules, floats along in the veins into 
the heart, through the lungs, and then by the way of the 
ventricle into the arteries and capillaries, where it comes 
in contact with the living cells of the various tissues. 
It is taken up from the plasma by these cells and either 
built into living protoplasm or oxidized within the proto- 
plasm to yield energy, or it may be deposited within the 
protoplasm in the form of fat globules. 

If one eats more starch and fats than are required for 
the energy of heat and motion, this material is usually 
deposited in the savings bank of the system, because the 
system is very economical, never wasting any food that it 
has taken the trouble to digest. The savings bank of the 
system is located in the connective tissue, and the sav- 
ings are deposited in the form of fat. If there is much 



HOW THE FOOD IS USED IN THE BODY 203 

saved, the individual may become quite '' fleshy," as we 
say. 

The proteid matter absorbed as peptone and changed to 
blood proteid, continues to accumulate in the blood until 
it is absorbed by the living cells and either built up into 
living protoplasm or oxidized within the cell protoplasm 
to yield energy. 

Remember : (1) Food taken into the alimentary canal 
must usually be digested before it is absorbed. Such sub- 
stances as water, salt, and certain kinds of sugar do not 
need digestion, but are absorbed in the form in which 
they are eaten. (2) Absorption is the taking up of sub- 
stances by the body ; for example, oil may be absorbed 
by the skin, oxygen by the lungs, and sugar, fats, water, 
peptones, salts, etc., by the lining of the intestine. (3) As- 
similation is building up of absorbed food into the living 
tissue of the body. (4) Foods do not yield their energy 
to the body until they are oxidized. Oxidation is the 
reverse of assimilation. Assimilation is a building-up 
process, while oxidation is a puUing-down process. As- 
similation requires energy to bring it about, while oxida- 
tion yields energy. Motion, heat, and light are kinds of 
energy. 

3. THE GENERATION OF LIFE ENERGY 

The first lesson in nutrition tells why we eat. You 
remember that we eat food for the energy that it contains, 
and the whole processes of digestion, and circulation, and 
respiration all lead up to the generation of this energy, to 
obtain which the food was taken. We traced the food, 
which is the fuel of the body, into the living cells ; we 
have traced the oxygen into the living cells. The next 



204 PHYSIOLOGY 

step is the oxidation of this body fuel and the generation 
of life energy. 

Muscle tissues are by far the larger part of the active 
tissues, so that we are prepared to expect that most of the 
energy liberated by the body will be muscular energy. 
One usually thinks of muscular energy as energy of 
motion, because we use our muscles in our movements; 
but the energy of motion is not more important than the 
heat energy which the muscles generate. The muscles 
generate motion during only a small part of the time, but 
they generate the energy of heat continually, never stop- 
ping from the day of birth to the day of death, nor any 
single hour between these days. 

The glands of the body work only a part of the time, 
and some of the work which the glands do generates heat, 
while other parts of their work require energy from other 
sources. 

The nervous system generates a kind of energy peculiar 
to itself, which seems to be similar in many respects to 
electricity. There is some heat, also, generated in the 
nervous system. 

Where fuel is being oxidized, or burned, we usually find 
smoke, ashes, and gases. The smoke is composed of 
unburned carbon and water ; the ashes represent the 
mineral matter of the fuel ; while the gases are repre- 
sented, for the most part, by carbon dioxide. The 
oxidation in the body is similar to the oxidation in a 
locomotive in many respects, and there are waste matters 
resulting from body oxidation, as there are waste matters 
resulting from fuel oxidation. Water is formed; carbon 
dioxide is formed ; and there are certain substances which 
may represent the ashes, substances which contain nitro- 
gen. These substances are as poisonous to the flame of 



HOW THE FOOD IS USED IN THE BODY 205 

life, if they are allowed to collect in the body, as the 
carbon dioxide which collects in the drinking glass is 
poisonous to the candle flame. 

If the unoxidized nitrogenous substances are not thrown 
out of the system, they will clog it up and destroy its 
proper action, just as surely as the cinders and ashes of 
the locomotive would put out the fire if they were not 
raked out. 



CHAPTER IX. — HOW THE WASTE MATERIALS 
ARE THROWN OUT OF THE BODY 

Ix the previous lesson we learned that active cells 
are constantly forming products of oxidation which are 
poisonous to the system, and which, if not thrown out, 
would very soon destroy the life. These products can 
be grouped into three classes : (1) carbon dioxide ; (2) 
water; (8) nitrogenous substances and mineral salts. 

The carbon dioxide is carried to the lungs b}^ the blood, 
and thrown out of the system in the way described under 
Respiration. The water that is formed in the system, to- 
gether with large portions of that which is taken in as drink, 
is given off from the system in two different Avays, besides 
that which leaves by way of the lungs and intestines. 
First, it is given off by the skin in the form of perspira- 
tion. There are innumerable fine pores, those lining the 
palm of the hand being large enough to be seen with a 
common magnifying glass. These pores, which cover the 
whole surface of the body, are the openings of minute 
glands which lie in the skin, and whose work it is to form 
the sweat or perspiration. These glands are called the 
sweat glands. 

When we were studying about animal heat, we found 
that the temperature of the body was controlled in part 
by the rate at which water was poured out on the skin in 
the form of perspiration. The work which these sweat 
glands do in helping to regulate temperature is very 
much more important than the work which they do in 

206 



HOW THE WASTE MATERIALS ARE THROWN OUT 207 

throwing out the water of the system, because the water 
can go out of the lungs, intestines, and kidneys, but there 
is no tissue or organ that can, in man, take the place of 
the skin in the regulation of the temperature. 

Let us, then, remember that of two kinds of work which 
the skin does, the heat-regulation part is very much more 
important than the work which it does in ridding the 
system of a part of the water. 

But the most important organs for throwing out waste 
materials are the kidneys. 

1, EXCRETION BY THE KIDNEYS 

The process of throwing out waste material from the 
body is called excretion. We have seen, from what has 
just been said, that the lungs, and skin, and intestines are 
all organs of excretion, or excretory organs. The kidneys 
differ from other excretory organs in the fact that they 
have no other function, but devote their whole time and 
energy to the work of separating out from the blood 
waste substances which, if retained in the body, would 
soon cause convulsions and death. 

The kidneys are two in number, and about long enough 
to reach across the palm of the hand. They are located 
in the back part of the abdominal cavity, back of the thin 
membrane which lines the cavity, and which holds them 
in place. They are located about opposite the small of 
the back, one on either side of the spinal column. Each 
receives a large branch from the abdominal aorta, and 
each gives off a large branch w^hich passes to the inferior 
vena cava (Fig. 48). From each kidney a tube passes 
down to the bladder, which is located in the lower part of 
the abdominal cavity, in front. 



208 



PHYSIOLOGY 



The kidney is a glandular organ, and the arterial blood, 
after passing into the kidney, is distributed in fine arteri- 
oles to an innumerable num- 
ber of little capillary tufts, 
where the excess of water 
of the blood is filtered out, 
and passes along a little 
glandular tube, which is 
surrounded by a network of 
capillaries. The cells of 
this glandular tube take 
out from the blood in the 
capillaries all of the nitro- 
genous waste matter and 
pour it into the canal of 
the tube, where it is washed 
along b}^ the water into a 
common receptacle in that 
part of the kidneys where 
the blood vessels enter, and 

from this common receptacle 
Fig. 48. — The kidneys and bladder as . i t i 

they would look if viewed from it llows down the little 

behind, a, kidneys; 6, abdominal drainage tube to the blad- 

aorta; c, vena cava; d, ureters, t ? . 

tubes to carry urine to the bladder ; der, where it collects, and 
e, bladder. from which it is from time 

to time given off. 




2. THE HYGIENE OF THE LIVER AND KIDNEYS 
I. HOW TO TAKE CARE OF THE LIVER 

It is not easy for a person to tell the condition of his 
liver. One of the functions of the liver is to form bile. 
When the liver is in a condition to form bile pro23erly, it 



HOW THE WASTE MATERIALS ARE THROWN OUT 209 

is usually in a condition to do the rest of its work. 
When the bile is improperly formed, or formed in too 
small quantities, a person becomes constipated, and that 
which passes the bowels is too light in color. To guard 
against this condition, which is a very serious one, and 
which always leads to the derangement of other functions 
of the body, one should avoid overeating and should 
take plenty of exercise in the open air. If, through care- 
lessness, the system gets in the condition above mentioned, 
one should consult a physician for more extended advice 
than can be given in this brief book. 



II. HOW TO TAKE CARE OF THE KIDXEYS 

The urine should be a light yellow color, and perfectly 
clear, and no sediment should collect if it stands in a 
receptacle for twenty-four hours. The kidneys are in- 
jured by overwork; and, as the principal work of the 
kidneys is to excrete nitrogenous waste matter, it is easy to 
see that the eating of too much nitrogenous food, or pro- 
teid food, will result in the kidneys being overworked. 

The best rule to follow, if one wishes to keep these 
organs in healthy condition, is to eat sparingly of meat, 
and drink plenty of water. Most people drink too little 
water ; few people drink too much water. 

If the. urine becomes unusually dark in color, or if there 
should be a reddish sediment when it stands in a recep- 
tacle, one should drink all the water he can for a few 
days. Lemonade is wholesome for these organs which 
eliminate the waste materials from the body. The lemon- 
ade should be taken with little sugar, and not too strong, 
and may be taken in large quantities, especially in 
summer. 



210 PHYSIOLOGY 



III. THE EFFECTS OF ALCOHOL UPON THE LIVER AKD 

KIDNEYS 

Dr. Wilkins ^ says that the coloring matter of the bile 
cannot be properly oxidized in the presence of alcohol, 
and that the work of the liver must be deranged while 
alcohol is passing into the system through that organ. 

Dr. McMichael ^ says, '' Alcohol produces disease of 
the liver and of the kidneys because these glands are most 
concerned in the throwing out of any poison, and are 
always, until they are deranged in structure, engaged in 
removing it from the body." He says that the disease 
almost universally caused in the liver by alcohol, is one 
in which the connective tissue framework of the liver in- 
creases, taking the place of the liver cells, until the liver 
is no longer able to perform its function. 

The kidneys may undergo a change similar to that of 
the liver when alcohol is used, even in moderate amounts, 
for a long period. 

Such profound changes in organs whose work is so 
important to the system, are naturally accompanied by 
derangements of the general health, and at last are fre- 
quent causes of death. 

1 New York Medical Journal, September 22, 1894. 

2 Dietetic and Hygienic Gazette^ May, 1897, p. 279. 



CHAPTER X. — THE SKIN — HOW IT IS MADE, ' 
AND WHAT IT DOES — HOW TO TAKE CARE 
OF IT 

The skin has been mentioned several times in the pre- 
ceding lessons. We have found that it is a most impor- 
tant organ for the regulation of the temperature, and that 
it takes a part in the throwing out of waste materials 
from the body ; but its most important work has not yet 
been mentioned. You remember that the little plant, 
described in the first lessons of this book, was provided 
with a thin, transparent skin ; you remember that the 
bark of a tree was called its skin, and you know that 
the bark of a tree protects from injury the sensitive 
tissues which lie beneath it. 

In a similar way, the skin of animals is an organ of pro- 
tection ; and although this organ may perform, or assist in 
performing, several other functions, this one is the most 
important of all. The skin is made in such a way as to 
adapt it especially for its principal function, protection. 

1. HOW thp: skin is made 

The skin is composed of two layers ; one of these is 
composed of living tissues, and the other of nonliving tis- 
sues. Figure 49 shows the living layer of skin at Dm, 
This layer, which is called the dermis, or true skin, is 
composed of a network of fibers of connective tissue, 
within which lie the hlood vessels and lymphatics^ which 

211 



212 



PHYSIOLOGY 



bring the nourishment to the tissues ; the nerves^ which 
make the skin sensitive to touch and to changes of temper- 
ature ; the oil glands^ which pour their oil out on the sur- 




\Dm 



Fig. 49. — Vertical section of the skin, magnified: a, scarf skin ; h, pigment 
cells; c, papillae; Dm, true skin; e,f, fat cells; g, sweat glands; A, outlets 
of sweat glands : i, their openings on the surface of the skin ; k, hair follicle ; 
/, hairs projecting from the skin ; m, hair papilla ; n, hair bulb ; o, root of 
hair ; p, openings of oil glands ; Ep, epidermis ; Sh, subcutaneous connective 
tissue. 



face of the skin ; the hair follicles and the ducts of the siveat 
glands. 

This living part of the skin is very elastic, adapting 
itself perfectly to the curves of the body and the bending 
of the joints. Notice in the figure that the hairs have 
their roots in this true skin. Each hair grows from a 
papilla (Fig. 49, r/z); this papilla is provided with a nerve 



THE SKIN 213 

fiber and a tuft of capillaries. From the surface of this 
papilla the hair grows, thus pushing the hair out of the 
follicle, so that the hair becomes longer and longer as it 
grows at the papilla. 

The oil glands are located on either side of the hair 
follicle, and pour their secretion into the follicles beside 
the hair. This passes along through the epidermis, and 
pours out upon its surface around the hair. Notice that 
the surface of the true skin is rough, the prominences 
reminding one of a mountain range. These prominences 
are called papillae. Within every papilla there are either 
nerve endings or tufts of capillaries. The nerve endings 
make the surface of the skin sensitive, and the capillaries, 
besides bringing nourishment, bring the blood very near 
to the surface, where it may be cooled or where it may 
warm the surface. 

The papillae of the true skin are not exposed to the 
air, but are covered with a deep protective layer^ called 
the cuticle, or the epidermis. The cuticle is formed by 
the true skin ; the cells of the cuticle which lie next to the 
true skin are living cells. They draw their nourishment 
from the true skin, and keep dividing and forming new 
cells. These new cells are pushed out from the true 
skin until they get so far from the blood and lymph of 
the true skin that they can no longer get nourishment, 
and so they die. The dark line between a and b in the 
figure shows where this change takes place. 

That portion of the cuticle that is darker in the figure 
represents the dead scarfskin. Now as these cells are 
constantly forming on the surface of the true skin, the 
scarfskin would become enormously thick if its surface 
layers were not rubbed off by friction, such as that of the 
clothing. The cuticle is the protective tissue of the 



214 PHYSIOLOGY 

whole body ; the dead cells of its surface are not sen- 
sitive. Pressure upon its surface is felt because it 
presses through the epidermis upon the sensitive papillae 
beneath. 

The cuticle alone is not sufficient protection for the 
body, so most surfaces of the bodies of the mammals are 
provided with hair. Notice the back of your arm, and 
you will see great numbers of fine hairs growing ; these 
hairs protect the surface of the skin. They are especially 
thick upon the head, and when man lived in a savage 
state the matted hair was usually the only protection for 
the head. 

The tips of the fingers and toes are protected with nails. 
The papilla through which the hair grows corresponds to 
a papilla at the surface of the true skin, and a hair which 
grows from the surface of the hair papilla corresponds to 
the cuticle growing from the surface of the papilla of the 
true skin, so that we can see that the hair is modified 
cuticle. In a similar way the nails represent modified 
cuticle, and grow from the surface of the modified papillae. 
The teeth grow from modified papillae, and also represent 
modified cuticle. The same thing is true of the feathers 
of birds, the scales of fishes and reptiles, and the hoofs, 
horns, and claws of the lower mammals. If you think of 
the use to which these animals put these structures, you 
will see that they are all used for protection except the 
teeth, which, although used somewhat for defense, may 
also be used for other purposes. 

The work of the skin is first of all protection. In most 
mammals the protection against extreme changes of tem- 
perature is provided for by a thick coat of hair or fur. 
In birds the coat of feathers performs a similar service. 
At first it may seem that the horse's coat could not be 



THE SKIN 



215 



quickly changed from a thin one to a thick one, but that 
he must wait for the spring shedding of his thick winter 
coat in order to have a summer coat, which is thickened 
up by a new growth of hair in the fall for winter; but the 
horse may change the thickness of his coat in a few min- 
utes. If you will look at the hairs on the back of your 
arm you will see that they do not come straight out of the 
skin, but they come out obliquelj^ and all that are near 
together lie in the same direction. Each hair has a little 
muscle attached to the end of its follicle, as shown in 




Fig. 50. — Diagram showing at A the hairs lying down and the muscles at 
rest. At B the muscles have contracted, pulling the hairs up straight, thus 
making the coat much thicker and warmer. 



Figure 50. When the skin is warm, the hair lies down as 
shown in position A, that makes the whole coat of hair 
compact. When the cold strikes the skin, the muscle of 
each hair contracts and draws it up so that it stands per- 
pendicular to the skin. This makes the coat of hair very 
much thicker than it was before and keeps the animal 
correspondingly warmer. In man the hair which covers 
the general surface of the body is so thin and short that it 
cannot keep the body warm, but the muscles contract just 
the same and pull the hairs up, pushing up a little point 



HALL'S PHYS. 



-14 



216 PHYSIOLOGY 

of skin about each hair. This appearance of the skin is 
called goose flesh. 

The cuticle protects the delicate dermis from friction 
and pressure. If the friction and pressure are severe, the 
cuticle becomes thicker and more dense than it is over 
the general surface of the bodj^ Look at the palms of 
your hands and see if you have not little calluses. The 
cuticle on the bottom of the foot is much thicker than 
on the top of the foot. If the shoe does not fit perfectly, 
a thickened callus may form where it presses or rubs the 
foot. If this thickened callus becomes hard it may make 
the dermis beneath sensitive and sore. We call this 
condition a corn. 

Next to the function of 2^^*otectio7i^ the most important 
work of the skin is the regulation of temperature mentioned 
above, and next is the part which the nerves of the skin, 
together with modified portions of the skin, play in warn- 
ing the system of danger or of changes. This function 
of the nerves of the skin is called sensation. Another 
but comparatively unimportant function of the skin is 
excretion, 

2. THE HYGIENE OF THE SKIX 

I. CLEANLINESS 

The oil which is poured out upon the surface of the skin 
is perfectly clean, but it very readily collects dust and 
other impurities of the air. The scarfskin is continually 
being shed in minute scales composed of a few thin cells. 
If these were not removed from the surface they would 
soon collect in sufficient quantities to be visible as minute 
scales. The most important source of uncleanness of the 
skin is the perspiration which is constantly being poured 
out upon the surface of the skin. 



THE SKIN 217 

Figure 49 shows the little coiled sweat gland in the loose 
tissue below the true skin. This sweat gland takes up 
water and various other substances from the blood, and 
pours them out upon the surface of the skin. 

Sometimes we are not conscious of the perspiration 
because it does not make the surface wet, that is, because 
it escapes in the form of vapor from the pores ; that kind 
is called insensible perspiration^ but when it comes in large 
enough quantities to be condensed, and make the skin 
moist, then we call it sensible perspiration. The water of 
the perspiration evaporates to cool the body, but the salt 
and other solids remain upon the surface of the skin. 
This, mixed with the oil, the little scales of scarfskin, and 
the dust collected from the atmosphere, will in a very 
short time make the surface of the body unclean. 

A general bath^ in which use is made of soft water and 
soap, followed by thorough rubbing with a coarse towel, 
is a most efficient method for insuring the cleanliness of 
the skin. For persons in the ordinary occupations a 
general bath such as that described is not necessary oftener 
than once or twice a week ; if soap is used oftener, it is 
likely to make the skin dry and rough ; if a warm bath is 
taken oftener, it is likely to relax the skin and make the 
person take cold easily. A general rule for the use of 
soap and water for cleansing the body is : use it just as 
freely and just as frequently as is necessary to keep the 
body clean ; the hands may need it several times a day ; 
other portions of the body may not need it oftener than 
once a week. 

II. THE MOKNING BATH 

The warm water cleansing bath, because of its relaxing 
effect, may best be taken in the evening, especially during 



218 PHYSIOLOGY 

the cooler seasons of the year, but the cold water tonic bath 
may best be taken in the morning. A tonic bath may be 
taken either as a plunge bath, as a shower bath, or as a 
sponge bath. In any case the surface of the body should 
be wet only for a few moments in water of varying tempera- 
ture from tepid to cold, and the wetting should be fol- 
lowed by a vigorous rubbing with a coarse towel, and the 
rubbing continued until the whole surface of the body is 
red and glowing. Instead of making one take cold more 
easily, this treatment fortifies one against the feeling of 
cold or taking cold. It takes a very strong constitution 
to stand a cold plunge bath ; even a cold shower, lasting 
but a moment, is not advisable for a weak constitution 
unless the glow comes quickly. The safest tonic bath 
for a person not in vigorous health is a cold sponge bath 
on one portion of the body at a time ; each portion in turn 
being exposed, sponged, and rubbed until aglow. 

III. CLOTHING 

Life in the changeable climate of the temperate zone 
makes it necessary for man to have some other protection 
than that which Nature provides him. Besides this prime 
necessity^ there is the inclination on the part of all civilized 
human beings to wear clothing. Primitive man dressed 
in the skins of animals ; in the colder climates the over- 
coat made from the pelts of animals is the best protection 
against the low temperature. 

Clothing is made mostly from wool, cotton, silk, linen, 
leather, and fur. A fundamental rule for the clothing 
of the body is, clothe the body so as to make it comfort- 
able. To be comfortable the clothing must fit the body 
closely enough to conform readily to all of its move- 



THE SKIN 219 

ments. Among these body movements must be mentioned 
first, the resi^iratory movements ; no person should wear 
clothing so close about the waist as to hinder in any way 
the freest movements of respiration. The movements of 
the arms should be perfectly free and unhampered by the 
clothing. 

The shoes should not be so tight that one cannot move 
his toes ; if this rule is not observed the toes will become 
distorted and covered with corns. Because of the per- 
spiration which is constantly going on and the shedding 
of the scarfskin, garments that are worn next to the skin 
in the daytime should be removed at night. 

IV. THE INFLUENCE OF ALCOHOL UPON THE SKIN 

As already stated in a previous lesson, alcohol dilates 
the arterioles and capillaries of the skin. If alcohol be 
used in comparatively small amounts for a long period of 
time, the capillaries of the skin become permanently di- 
lated, thus giving the skin, especially of the face, a very 
red appearance, and the little dilated capillaries may be 
seen running their crooked course just beneath the surface 
of the skin. When the skin becomes thus changed, it 
cannot properly perform its portion of the work of 
excretion, and so the kidneys have to do a portion of 
the work which the skin ought to do, and thus they 
become overworked. 

3. THE SKIN AS AN ORGAN OF GENERAL 
SENSATION 

The nerves of the skin have been mentioned. Most 
of the nerve endings are sensory nerves, whose work it is 
to bring to the brain messages announcing the condition 



220 PHYSIOLOGY 

of the skin or the condition about the skin. Figure 51 
shows a thin slice of the true skin, with four papillae on 
its surface ; two of these paj)ill?e have capillary loops, and 
are therefore called vascular papilloe^ while two of them 
have curious little bulb-shaped nerve endings, which are 
organs of the feeling, or tactile corpuscles, and so the 
papillae which have these corpuscles are called tactile 
papillcB. 

There are other kinds of nerve endings in the skin. 
Some nerves end in fine fibrils, which pass up into the 
lower layer of the cuticle, but all these nerves bring 
sensation to the brain, and are therefore called sensory 
nerves. All parts of the skin are sensitive to touch and 
to changes of temperature, though some parts of it are 
more sensitive than others. The finger tips and the lips 
and tongue are more sensitive to touch than any other 
parts of the skin. The reason why these portions of the 
body are more sensitive to touch is because they have 
been most used, and, therefore, most developed. Because 
the senses of touch and of temperature are possessed by 
all parts of the skin, these senses are called general senses. 
A special sense is one which possesses a special organ. 

Taste, smell, hearing, and sight, possessing special 
organs in the tongue, nose, ears, and eyes, are called 
special senses ; while touch, temperature sense, and the 
sense of position of the body, are general senses. There 
are^ therefore^ four special senses and three general senses. 

T. THE TACTILE SENSE 

How lightly can you touch the tip of one of the hairs 
on the back of your hand or arm without feeling it ? 
How small a piece of match stick can you drop upon 



THE SKIN 



221 




Fig. 51. — a, nerve fiber; b, tactile papillae, 
containing a tactile corpuscle ; c, vascular 
papillae. [After Beuda.] 



the back of the hand, from the distance of two inches 
above the back of the hand and feel it? If you have a 
pair of draughtsman's 
compasses, or dividers, c 

or a pair of sharp- 
pointed scissors, see 
how close together you 
can hold the points and 
feel them as tAVO points 
when they touch the 
skin. At the finger 
tips, one can feel them 
as two points at a dis- 
tance of less than an 
eighth of an inch. 

How far apart must they be to feel them as two points on 
the back of the hand, on the palm of the hand, on the lips, 
on the cheek, on the throat, on the back of the neck, on 
the forehead ? When blindfolded, hoAV much can you tell, 
by feeling alone, about an object which may be handed 
to you ? 

II. THE TEMPERATURE SENSE 

Take a lead pencil which has been cooled in water or in 
cold air, and move the lead lightly over the back of the 
hand. Sometimes it will feel cold, and sometimes you have 
no temperature feeling at all. You will merely feel the 
lead moving over the hand. If you were to warm the 
lead by dipping the pencil into warm water, and move it 
similarly over the back of tlie hand, you Avould find that 
sometimes it would feel warm, and that sometimes you 
would have no sensation of temperature from this warm 
lead. From this we learn that the skin is divided into 



222 PHYSIOLOGY 

little areas, some of which are sensitive to cold, and some 
of which are sensitive to heat, while there are still other 
areas sensitive to neither cold nor heat. By cold and 
heat as used here, we mean, of course, substances colder 
than the skin or warmer than the skin ; because any- 
thing that is colder than the skin will feel cold, while 
anything warmer than the skin will feel warm. A thing 
which may feel cool sometimes may feel warm at other 
times, though at the same temperature. For example, if 
one has three dishes of water standing upon a table, the 
one at the right hand having cold water, the one at the 
left, warm water, and the one between the two, tepid 
water ; if he holds the right hand in the cold water, 
and the left hand in the warm water, for one or two 
minutes, and then takes the hands out and places them 
both in the tepid water, it will feel cold to the left hand 
and warm to the right hand. 

The temperature sense warns the animal of the changes 
of temperature in the air or water surrounding it, so that 
he may adapt himself to the change. A part of the adap- 
tation which the animal makes is an unconscious one, 
made through the sympathetic nervous system, and con- 
sists of the withdrawal of the blood from the surface 
when cold air first strikes the body, and a raising of the 
hair on end, as described above. 

III. THE SENSE OF POSITION 

If one were blindfolded and laid upon a table, he could 
easily tell if the table were lifted or tipped a little in one 
direction or another ; he could easily tell the direction, 
and he might even tell the amount, unless the movements - 
were very, very slow. One can walk with the eyes shut, 
or blindfolded, and maintain the erect position when rid- 



THE SKIN 223 

ing a bicycle. Though we do all these with the greatest 
ease, it is really a most difficult thing to do, if one were to 
stop to think about it, and something that takes a little 
child nearly as long to learn as to learn to read. 

Sensations are carried to the brain from the various 
parts of the skin. If one is standing or walking, pressure 
on the soles of the feet will tell in which direction the 
body is swinging. On whatever part of the body one 
rests, the skin from that part sends messages to the brain, 
which enables one to tell the position of the body, or 
changes in the position. The most important organ for 
sending messages to the brain regarding the position of 
the body is located within the internal ear. Through the 
aid of this organ, the brain knows of all movements of the 
head, whether from side to side, or forward and back, as 
well as all movements of the whole body through space, 
or the turning of the body. 

REVIEW OF THE SKIN AXD THE GENERAL SENSES 

1. The skin is composed of the dead cuticle and the living dermis. 
The dermis contains blood vessels, nerves, oil glands, hair follicles, and its 
surface is covered with mnumerable fine projections cslled papillce. 

2. The cuticle not having life is also without feeling. Its work is 
to protect the sensitive tissues which lie beneath it. The oil from the 
oil glands keeps the skin soft and protects it against the absorption of 
water. The hair, or the feathers, scales, oy plates, are modified cuticle 
and serve for protection. Nails, horns, and hoofs are also modified 
cuticle and serve for protection. 

3. The skin helps to regulate the temperature of the body by the 
perspiration. 

4. Because of the secretion of oil and of perspiration by the skin, 
this organ becomes soiled and must be cleansed with w^arm water 
and soap. 

5. A tonic morning bath with cool or even cold w^ater followed by 



224 PHYSIOLOGY 

brisk rubbing until the surface of the body is red and warm, is an 
excellent hygienic custom. 

6. Clothe the body in such a manner as to make it comfortable. 

7. If alcohol is used in moderate quantities for a long period of 
time, the capillaries become permanently dilated, thus giving the skin 
a permanent red color. 

8. There are three general senses and four special senses. The 
general senses are : Touch, or the tactile sense, the temperature sense, 
and the sense of position of the body, 

9. How may one test the tactile sense ? Where is this sense most 
acute? Is it more acute in some persons than in others? 

10. How may one test the temperature sense ? Why are animals 
provided with this sense? How does the horse adapt himself to a 
sudden change m the temperature from warm to cold? How does 
man adapt himself under similar conditions ? 

11. How is the brain made conscious of the position of the body 
when one is standing, sitting, or lying ? Of what use is this sense ? 



CHAPTER XL —THE SPECIAL SENSES — HOW 
ONE KNOWS WHAT IS GOING ON ABOUT 
HIM 

The preceding lesson described the general senses, which 
are so called because they do not possess a special organ. 
The special senses, on the other hand, are so called because 
the sensation is received by a special organ, which has no 
other function, and which is specially fitted for that par- 
ticular function. 

1. TASTE AND SMELL 

I. THE SENSE OF TASTE 

The special organ of taste is the taste bud, of which there 
are many hundreds, perhaps thousands, located on the sur- 
face of the tongue, and perhaps sparingly on the palate 
and sides of the pharynx. If you examine the surface of 
the tongue in the looking-glass, you will notice little red 
dots all over it. These dots are little funguslike papillae. 
If you can see the tongue very far back, you may see sev- 
eral very much larger papillae. All around the sides of 
the large papilhe at the base of the tongue and the small 
funguslike papillae, there are little spherical bodies, com- 
posed of many spindle-shaped cells, between which lie the 
fine hairlike endings of the nerves of taste. 

When a fluid substance, or a solid substance dissolved 
in the fluid, or one which ma)^ be dissolved by the saliva, 
is taken into the mouth, it comes into contact with these 

225 



226 PHYSIOLOGY 

minute taste buds, passes in between the spindle-shaped 
cells which form the taste buds, and stimulates the end- 
ings of the nerves of taste. This nerve sends the message 
to tlie brain, and one becomes conscious of the taste of 
the substance. Many of the sensations which we call 
taste are quite as much smell as taste ; the flavor of coffee 
and of roast meat is a sensation largely due to the sense 
of smell rather than to that of taste. Sensations which 
are combinations of taste and smell should be called 
flavors. 

There are only four different kinds of taste, — salt^ sour^ 
bitter^ sweet. Most of the sensations which come to us 
while we are chewing our food, and especially most of the 
agreeable sensations, are really flavors, and not taste at 
all. When one has a cold in the head, and both nostrils 
are completely stopped up, so that he can breathe only 
through the mouth, the food tastes flat and flavorless. 
This is sufficient proof that the flavors depend upon a 
combined sensation of taste and smell. 

Not all parts of the tongue are equally sensitive to these 
different tastes. The back part of the tongue, in the neigh- 
borhood of the large papillae, is especially sensitive to bit- 
ter ; the sides of the tongue are especially sensitive to acid ; 
the middle of the tongue is especially sensitive to salt ; 
and the tip of the tongue, to sweet. 

II. THE SENSE OF SMELL 

The specialized organ for smell is the upper part of the 
nose. The lower part, from the nostrils directly back- 
ward, is one of the air passages and part of the respiratory 
system, but all the upper part of the nose out of the 
direct line of breathing is devoted exclusively to the sense 
of smell, and there are nerve cells in the nose which stand 



THE SPECIAL SENSES 227 

in the mucous membrane among the cells which pave the 
membrane. 

Odorous substances, in the form of gas or of minute 
particles, may pass in with the inspired air or may pass 
up from the pharynx with the expired air, as is the case 
when one is chewing food. These odorous substances 
become dissolved in the moisture which covers the mem- 
brane in the upper passages of the nose. They then come 
in contact with the nerve cells of smell in the membrane, 
and these nerve cells send a message to the brain, and one 
becomes conscious of the smell; i.e. he receives the sen- 
sation of the smell. 

The different kinds of taste we found to be limited to 
four, but the different kinds of smell are innumerable. 

Nature provides animals with these senses for a purpose. 
It seems to be Nature's plan that animals should use these 
senses in the choice of their foods. In the case of beasts 
of prey, the sense of smell may be used in tracing their 
prey. These senses guide herbivorous animals in the 
choice of herbage. A poisonous iveed is rarely mistaken hy 
them for a wholesome one. 

Man can be guided by his sense of smell as to the 
wholesomeness of the air which he is breathing, and his 
taste will serve in part as a guide to the choice of food. 

An odor is remembered longer than any other sensa- 
tion. This sensation calls up more quickly and forcibly 
some past experience than does any other sense im- 
pression. 

To smell things simply because they produce a pleasing 
sensation, and to taste and eat or drink things simply 
because the taste or flavor is a pleasing sensation, is a 
perversion of Nature's laws which may be observed in 
man only, of all animals. 



228 



PHYSIOLOGY 



2. HEARING 



The ear is the special organ of the sense of hearing. 
That part of the ear which we can see on the outside of 
the head is only a sort of funnel for catching the sound 
and conducting it into the part of the ear where the sound 
is heard. The outer ear, together with the passage to 
the ear drum, is called the external ear. The middle ear^ 
or eardrum^ is a little cavity in the solid bone of the side 
of the head. Still deeper in the bone is the internal ear^ 

composed of a vestibule^ 
from which open a 
coiled chamber similar 
to a snail shell, called 
the cochlea^ and three 
semicircular canals. 

The middle ear is 
called the tympanum^ or 
eardrum, because of its 
resemblance to a drum. 
As you know, a drum 
has at least one drum- 
head, which is a vibrat- 
FiG. 52. — Section of the ear, showing the ing membrane. Every 

relative positions of the external, middle, r|i'm;Q Jc T3rovided with a 
and internal ear. [Tracy.] . -'- . 

side opening. If this 
side opening were not provided, the membrane would not 
vibrate freely, and the drum would have a dead, muffled 
sound. The side opening into the tympanum is provided 
by the Eustachian tube^ a small canal which passes from 
the pharynx up to the middle ear. 

These parts which have been described are shown in 
Figure 52. Study carefully this figure. Notice that the 




THE SPECIAL SENSES 229 

middle ear, or tympanum, is divided from the canal which 
passes in from the external ear by the drum membrane^ and 
that it is divided from the vestibule by a little membrane 
across wliat is called the oval windoiv. Between the drum 
membrane and the oval window is a chain of three hones. 
The one which is attached to the drum membrane is called 
the hammer^ the one which is attached to the membrane 
of the oval window is called the stirrup, and the one 
between, fastened to the hammer at one end and to the 
stirrup at the other, is called the anvil. 

When the sound which passes in through the canal of 
the external ear makes the drum membrane vibrate back 
and forth, the hammer vibrates with "it, and passes the 
vibration on through the anvil and stirrup to the mem- 
brane of the oval window. So the sound vibrations 
received by the ear are thus carried direct to the mem- 
brane of the oval window. The vestibule, cochlea, and 
canals of the internal ear are filled with liquid ; the 
vibrations of the mem_brane of the oval window set the 
liquid into vibration. 

There is stretched across the cochlea, from its center to 
its circumference, a membrane composed of thousands of 
little fibers lying side by side, some long and some short, 
those at the upper end being about twelve times as long 
as those at the lower end, reminding one of a harp with its 
long and short strings. The vibrations of the liquid set 
these fibers to vibrating. Upon the fibers stand cells, 
about which are the fibers of the auditory or hearing 
nerve. The vibrations of the fibers stimulate the nerves, 
and we become conscious of the sound. 

The sense of hearing is one of the most useful to man 
and to other animals, because it may warn man of 
approaching dangers when they are still at a considerable 



230 PHYSIOLOGY 

distance. It enables him to hear at a great distance a 
call for help or a shout of warning. It enables him 
through conversation to communicate his ideas to others. 
Through the ears we are made conscious of the joys and 
sorrows of our comrades ; we hear their laughter as well 
as their sobs. 

It is a part of Nature's plan for the sense of hearing to 
be cultivated and gratified for simple pleasure. It may 
be observed even in the habits of the lower animals. The 
summer night concert of the frogs and crickets, and the 
summer morning concert of birds, are sufficient evidence 
that the voice and the hearing are to be cultivated 
together for the entertainment and the pleasure of one's 
self and others. Music is elevating and enriching in its 
influence. 

The most important thing to remember in the care of 
the ears is that no hard or irritating substance or instru- 
ment should be put into the canal of the ear, because there 
is danger of injuring the delicate drum membrane. If 
wax collects in the ear canal it may be gently removed 
with the little finger, covered with a handkerchief or 
wash-cloth. If the wax hardens in the ear, which fre- 
quently happens, causing some pain, it may be softened 
with one or two drops of sweet oil, or of fluid cosmoline, 
after which it can be easily removed with an ear spoon. 

3. THE SENSE OF SEEING 

The eye is the special organ of this special sense. The 
eye is one of the most complex organs of the body, 
and the sense of sight is the most important of the 
special senses. Figure 53 shows what you could see in a 
comrade's eye if you were to look at it very carefully, 



THE SPECIAL SENSES 



231 




Fig. 53. — The eyelashes and the tear 
glands : G, tear gland ; D, island around 
which the tears collect ; (7, tear canals ; 
)S, tear sac; B, nasal duct through which 
the tears drain off into the nose. 



using, perhaps, a reading glass to magnify the parts some- 
what. The eyeball is movable under the lids, and has a 
dense coat which shows 
in the corners of the 
eyes, but directly in 
front you see the black 
pupil of the eye, sur- 
rounded by the colored 
disk, brown in some eyes 
and blue or gray in 
others. 

The eyeball is so deli- 
cate in its construction 
that^it must be very 
thoroughly protected 
from dust and all other 
injurious things. These 
protective parts, including the lashes, the brow, and tear 
apparatus, are called the appendages of the eye. The eye- 
lids are the most important protection of the eye, keeping 
its transparent central portion moist and free from dust. 
Notice that the margins of the lids are supplied with long, 
stiff hairs. These are the eyelashes, and they assist in 
protecting the eye from dust. On the edges of the lids, 
notice the little dots. These mark the openings of minute 
oil glands within the lids. These oil the edges of the lid, 
to keep the tears from overflowing. 

Above the outer corner of the eye and under the brow 
is a gland about as large as the last joint on your little 
finger. This is the tear gland, and its secretion, mostly 
water, with a little salt and mucus in it, pours through 
the little ducts under the upper lid. When one winks 
the eye, the upper lid spreads the tears over the surface, 

hall's phys. — 15 



232 PHYSIOLOGY 

thus washing off the dust and making the surface fresh 
and bright. The tears are constantly evaporating from 
tlie surface of tlie eyeball, but there are always some left 
over, and these gradually collect down at the inner corner 
of the eye around a little island, which is marked D in 
the picture. On either side of this little island are two 
minute pores, leading into the tear canals, marked G in 
the picture. The two canals come together in what is 
called the tear sac, from Avhich a large duct, called the 
nasal duct (^), conducts the tears into the nasal passage. 
If the tears flow rapidly, as when one is crying, they may 
come too fast to flow off through the little canals, and so 
may overflow upon the face; in that case they will also 
flow freely from the nose. 

Among the appendages of the eye are the muscles 
which move the eye. These are six in number. One 
muscle turns the eye inward toward the nose, while the 
one opposite to it turns it outward. Then there are 
muscles which turn it upward or downward or obliquely. 
Sometimes one of these muscles is permanently contracted, 
thus keeping the eye turned in ; then we say the person 
is cross-eyed, or has a squint. A specialist is usually 
able, by a simple operation, to loosen the muscles enough 
to straighten the eye. 

The eyeball is nearly spherical, and has a dense outer 
coat called the sclerotic coat. The front part of this 
coat is curved outward and transparent, reminding one of 
a watch crystal. This is called the cornea, and through 
this the rays of light pass into the ej^e (Fig. 54). 
Just within the sclerotic coat is the choroid, which is a 
loose-meshed tissue, full of blood vessels and nerves. 
This coat contains an important muscular body called 
the ciliary muscle, and it is this coat which makes the 



THE SPECIAL SENSES 



233 



little colored curtain called the iris. This little curtain, 
the iris, is like the diaphragm of a camera, and through it 
there is a circular opening called the pupil. The mus- 
cles which it contains may dilate or contract the pupil 
according to the amount of light, or according to whether 
the object looked at is near or far away, — contracting to 
see near objects and dilating to see distant objects. The 




Fig. 54. — Horizontal section of the eyeball: d, sclerotic coat; c, cornea; e, 
choroid coat; i, iris; Aq, aqueous humor; a, crystalline lens; /i, vitreous 
humor; h, retina; 0, optic nerve; cm, ciliary muscle; R, place where 
muscles were attached. 

light which enters the eye through the cornea, passing 
through the pupil of the eye, must be focused upon the 
sensitive portion of the eye, the retina. The focusing is 
done by the crystalline lens. The crystalline lens is held 
in place by little ligaments, which pass out from the 
ciliary muscle. The contraction of this muscle will cause 
the lens to become more convex, thus focusing the light 
from near objects upon the retina. 



234 PHYSIOLOGY 

The retina is composed of two coats, the outer coat 
consisting of a sepia-bhick pigment which absorbs the 
light, Avhile tlie inner coat (shown white in the figure) 
consists of the nerve cells of sight. The eye nerve or 
optic nerve passes from the base of the brain direct to the 
ball of the eye, and enters it at (9, Figure 54, the fibers 
spreading out to pass to the nerve cells of the retina. 
The most sensitive part of the retina is just at the outside 
of the optic nerve, and is marked m,l, in the figure. 
That part of the eyeball in front of the crystalline lens, 
and back of the cornea, is filled with a limpid, transpar- 
ent fluid called the aqueous humor ^ while that part back 
of the crystalline lens and comprising most of the ball is 
filled with a viscid liqaid of much greater consistency 
than the aqueous humor, which is called the vitreous 
humor. 

These general rules may be given for the care of the 
eyes : — 

I. Never read by a dim light. 

II. Never read by a flickering or rapidly changing light. 

III. Never read in too bright a light, for example, when 
the sun is shining full upon the page. 

IV. Let the light shine upon the page and not upon the 
eyes. The light should fall upon the page from the side 
or from behind. 

When the eye is at rest, distant objects are focused 
upon the retina ; to see near objects it is necessary for 
the muscle which controls the lens to contract ; to look 
constantly at near objects requires a constant contraction 
of this muscle. We know how hard it is to keep a muscle 
contracted for a long time, and we can see that it would 
strain the eyes to look for a long time continuously at 
a close object, so we can appreciate the next rule. 



THE SPECIAL SENSES 235 

V. When reading a book or studying any close object, 
either close the eyes or look off at a distant object every 
few minutes to rest the eyes. If one has used the eyes 
too long and has tired them, bathing them in cold Avater 
is to be advised. If one cannot see clearly distant objects, 
or if one lias headaches that cannot be definitely traced to 
some other cause, he should consult a physician to see if 
the eyes need the assistance of glasses. The free use of 
either alcohol or tobacco may cause a very serious injury 
to the sight. 

During the last few years railroad managers have observed the 
injurious effect of alcohol upon their workmen when occupying posi- 
tions that require delicacy of touch, keenness of vision, and acuteness 
of hearing, ^ot long since a large railroad corporation investigated 
the conditions surrounding every accident that had occurred on its 
lines during the preceding five years. It was found that forty per cent 
of all accidents were due entirely or in part to drinking men. In 
eighteen per cent it was strongly suspected that the drinking habits of 
employees was the cause of the accidents. The company in a single 
year lost property to the amount of one million dollars through the 
incompetency of beer-drinking engineers and switchmen. 

Michigan has passed a law which imposes a heavy penalty upon those 
railroad companies which employ men who are in the habit of using 
alcoholic intoxicants. Railroad managers, as practical business men, 
are recognizing the utility of employing total abstainers as a measure 
calculated to reduce financial losses on account of accidents. 

Some railroad companies prohibit their employees from drinking 
any kind of intoxicants or entering a drinking saloon during working- 
hours, while other railroad companies demand from their employees 
the signing of a total abstinence pledge which shall hold good for 
every hour of every day. 

This action of railroad managers shows their axDpreciation of the 
doctrine that even small quantities of alcohol impair the organs of 
special sense, and that in order to do the best work in railroad busi- 
ness the workmen must have eyes, ears, and hands perfectly free 
from the poisonous influence of alcohol. — J. W. Grosvenor, M.D., 
Journal of American Medical Association, June, 1896, p. 126. 



236 PHYSIOLOGY 



REVIEW OF THE SPECIAL SENSES 

1. How many different kinds of taste are there? Name several 
pleasing flavoi-s. What is the special organ of the sense of taste? 

2. What is the special organ of the sense of smell? Name several 
odors or perfumes which are pleasing. 

3. What seems to be Nature's plan for the use of the senses of 
smell and taste ? 

4. Describe the special organ of hearing ; its three divisions and 
the way each division is made and the work it does. 

5. What reason have we for believing that it is in harmony with 
Nature's plan that we cultivate the taste for music ? 

6. How should the ear be cared for? 

7. Draw a picture of the eye, showing all of the principal structures. 
Describe the drawing, and tell what is the work of each one of the 
structures. 

8. Give the five rules for the care of the eyes. 

9. Why cannot railroad engineers do their work so well if they 
have been indulging in moderate drinks of alcoholic beverages? 



CHAPTER XII.— THE NERVOUS SYSTEM — 
THE BRAIN, THE SPINAL CORD, AND THE 
NERVES 

The subject of this chapter is not a new one. The 
reader will remember that in Chapter III of General 
Physiology, under the heading, " How the Different Organs 
are made to work in Harmony," the nervous system was 
studied at considerable length. This chapter will not be 
a repetition of what was given there, but an extension of 
it. In order to understand what is to follow in this 
chapter it will be necessary to review again carefully the 
chapter just referred to. To that end you may look up 
again the answers to the following questions. 

I. In what respects is the animal body similar to a large 
colony ? 

II. How are the different individuals of a colony made 
to work in harmony ? 

III. How is a railroad company able to send over its 
lines a large number of trains without having numerous 
collisions ? 

IV. Why is it necessary that the work of the stomach 
be done at any particular time ? Why cannot the stomach 
secrete its juice at any time ? 

V. What would happen if the change of rate of the 
heart beat or if the change of rate and depth of respiration 
should take place at any time without reference to what 
the muscles were doing ? 

VI. What two things are necessary in bringing harmony 

237 



238 PHYSIOLOGY 

of action among those who work for a great railroad 
company? (For example, see beginning of Lesson 2, 
Chapter III.) 

VII. What is a nerve trunk? a nerve fiber? a nerve cell? 

VIII. What is the sympathetic nervous system ? 

IX. How does the sjanpathetic system perform its work ? 

X. What is the relation between the sympathetic sys- 
tem and the spinal cord ? 

XI. How is a message sent from the brain to the 
muscles of the arm? (See Lesson 3, Chapter III.) 

XII. What is voluntary action? 

XIIL In how many directions must messages be sent 
when one sees something which he desires, and reaches 
for it? 

XIV. What is reflex action? 

XV. Does the brain receive any sensation in the case 
of a reflex action ? If so, when is this sensation received, 
before or after the act occurs? 

XVI. What is the relation betAveen voluntary action 
and automatic motion? 

XVII. What is hahit^ and what is its relation to 
automatic action ? 

1. THE STRUCTURE AND FUNCTION OF THE BRAIN 
I. NERVE CELLS 

Nerve cells are the most remarkable cells in the animal 
body, for their variety in shape, as well as for their size. 
Figure 55 shows a typical nerve cell. This cell came 
from the spinal cord. Some of the cell bodies in the 
spinal cord are so large that they may be seen with the 
unaided ej- e, and have branches reaching from the cord to 
the hand or foot. 



THE NERVOUS SYSTEM 



239 



Notice in this cell in Figure 55 how irregular the 
outline of the cell body is. Each little projection of 
the cell body passes out into a treelike branch, and because 
of their resemblance to a tree they are called dendrites. 

The nerve cell,, like other 
cells, is composed of proto- 
plasm. These cells have very 
large nuclei^ and one or more 
nucleoli. The protoplasm of 
the nerve cells is granular. 
There is usually a collection 
of pigment (Fig. 55, P) in 
each cell. The dendrites are 
prx)toplasmic branches of the 
cell. The dendrites bring 
messages to the cell. Through 
the dendrites the cell body 
may be in communication with 
numerous other cells. Though 
a cell receives messages from 
various sources, it can send a 
message in only one direction. 
One of the extensions of the 
cell is called a neurite. It is 
the neurite which carries the 
message away, and under no 
circumstances can the neurite 
bring messages to the cell, 
long dendrite which may bring a message from a long 
distance ; those nerve cells also have a neurite. The sen- 
sory nerves, which carry messages from the skin to the 
brain, are long dendrites ; the cell body is located near 
the spinal cord, and the neurite passes into the cord. 




Pig. 55. — A nerve cell from the 
anterior horn of the spinal cord. 
The Dendrites carry messages to 
the nerve cell and the Neurite 
carries messages away from the 
nerve cell. Neuroglia {N) is 
the supporting tissue. Insulat- 
ing material {S), pigment (P). 

Some nerve cells have a 



240 PHYSIOLOGY 



II. KERYE SUBSTANCE 



The substance of the central nervous system, that is, 
the spinal cord and brain, comprises two tissues, nerve 
tissue and supporting tissue. The supporting tissue is a 
very fine-meshed connective tissue called neuroglia (see 
Fig. 55, N), Only a small amount is shown in that figure, 
in order not to obscure the details of the nerve cell, but 
the neuroglia tissue fills all the space between the cells and 
nerves, serving really as a packing to hold the cells in place, 
as we use excelsior for packing. It is the nerve tissue, made 
up of nerve cells, which does the work of the system. 

III. NERVE CENTERS AND NERVE TRUNKS 

The cell bodies are not scattered promiscuously through 
the nervous system, but are gathered into groups. This 
seems to afford easier communication from one cell to 
another through their short-branched dendrites. Such a 
group of cells is called a nerve center^ and in its action on 
the nervous system is similar to the central office of a tele- 
phone system. To such a center there are fibers coming 
from a distance bringing messages, and from the center 
the message may be forwarded to one of the distant 
parts of the system. 

The nerve fibers which pass from the cell bodies or from 
nerve centers are insulated one from another through the 
means of a white substance which makes a sheath about 
each fiber. A bundle of these fibers is called a nerve 
tract while it is still within the spinal cord or brain, but 
when it emerges from these organs and passes out as a 
rounded nerve cord, we call it a nerve trunk. Because of 
the insulating material which surrounds the fibers, nerve 
trunks and nerve tracts are white in color, and because 



THE NERVOUS SYSTEM 



241 



of the protoplasm of which nerve cells are made, the 
nerve centers have a grayish color. This led the anat- 
omists and pliysiologists in times past to classify nerve 
substance as gray matter and white matter. 



2. THE SPIXAL CORD AXD BRAIX 
I. THE SPIXAL CORD 



Figure 56 gives a 
view of the whole central 
nervous system, with the 
-spinal cord as seen from 
behind. The nervous 
system may be said to 
comprise two organs : 
first, the brain ; second, 
the spinal cord. The 
spinal cord represents a 
series of important nerve 
centers, around which are 
grouped bundles of nerve 
tracts (Fig. 67). The 
grayish outline of the 
centers makes a figure 
something like the letter 
H when the cord is cut 
across ; and all the sub- 
stance outside of the H 
represents tracts or bun- 
dles of fibers which are 
passing upward toward 




Xerves to 
front of 
right leg. 



N"erves to 
back of 
right leg. 



Fig. 56. — Brain and spinal cord, with the 
thirty-one pairs of spinal nerves. 



242 



PHYSIOLOGY 



the brain or downward from the brain. Thiey are simply 
cut-off fibers in this picture (Fig. 57). 

The centers for motion in this spinal cord are in the 
front horns of the H. Reflex action has been described 
in Chapter III. If we make a careful study of Figure 57, 
we can see how this reflex action is brouglit about. Sup- 
pose something irritates tlie skin. A message is carried 
along tlie long dendrite reaching from the skin to tlie 




Fig. 57. — A diagram of a slice of the spinal cord as seen from behind, to show 
how the sensation is conveyed to the ganglia of the posterior root through 
the long dendrite D, thence to the cord through the neurite N. Arrived 
in the cord it may go to the brain as at ^' or i^". But instead of j^assing 
to the brain it may pass to the cells of the anterior gray horn, and cause a 
reflex act. 



nerve cell (the ganglion on the posterior root), and from 
this cell body a message is forwarded along the neurite 
into the posterior gray liorn of the spinal cord, whence it 
is communicated to the brain, as well as to the center of 
motion in the anterior gra}^ horn. Without waiting for a 
reply from the brain, the cells of motion in the anterior 
gray horn may send a message to the muscle through the 
anterior root along the motor nerve, as shown in the 
figure, and the muscle may contract, drawing the skin 
away from the irritating object before even the brain 
knows what is taking place. 



THE NERVOUS SYSTEM 243 



II. THE BRAIN 

Figure 56 shows the posterior view of the brain, com- 
posed of the great cerebrum, subdivided by the fissure into 
two hemispheres, below which is the much smaller cerebel- 
lum. Figure 58 shows more clearly the relative sizes of the 
cerebrum and cerebellum, and shows the brain from a side 




Fig. 58. — Side view of brain, showing the large cerebrum with its surface in 
folds and fissures, the small cerebellum below the back part of the cere- 
brum, and the medulla passing downward from the base of the brain. The 
word " Leg" shows where the brain is at work when it sends messages to 
the leg ; similarly for head, arm, face, and for the organs of speech. *' Hear- 
ing " and " Vision " show where the brain receives the sensations of hearing 
and sight. 

view. The surface of the brain is thrown into a series 
of very irregular folds, called convolutions. The pur- 
pose of these convolutions seems to be to increase the 
surface of the brain. It is upon the surface of the 
brain that the cells composing the nerve centers are 
located, while the internal portion of the brain is made 



244 PHYSIOLOGY 

up largely of white fibers connecting different brain cen- 
ters. By increasing the surface of the brain, the possible 
number of cell bodies is increased, thus increasing the 
brain activity. Highly civilized and educated races of 
men have brains which have more and deeper convolu- 
tions than do the half-civilized and ignorant savages. The 
savages, on the other hand, have more convolutions in 
their brains than does the monkey or the dog, and these, 
in turn, more than animals which stand still lower in the 
scale. 

The brain, then, represents a number of nerve centers 
grouped into a compact mass. Different brain centers 
preside over different functions of the body (Fig. 58, Leg, 
Arm, etc.). As there are nerve trunks passing from the 
spinal cord out to muscles and organs of sense, so from 
the brain there are nerve trunks passing out to muscles 
and nerve endings. Twelve pairs of these nerves extend 
from the brain and from the medulla to various structures 
of the head, face, throat, and thorax. 

The cerebrum contains the centers which preside over, 
or which are the seat of, consciousness of sensations, such 
as of sight, sounds, odors, and feelings, as well as the cen- 
ters of various emotions, such as fear, anger, love, hate. 
It is the seat of all thought, of reason, and of the will 
power. 

The cerebellum is the center which presides over the 
movements of the body and limbs, making these move- 
ments smooth and graceful. It helps to keep the body 
balanced in walking, standing, or riding. 

In the medulla oblongata, shown in Figure 58, there are 
numerous centers which preside over the movements of the 
heart, the respiratory organs, and the various organs of 
the digestive tract ; and which also preside over the con- 



THE NERVOUS SYSTEM 245 

strictors and dilators of the arteries, changing the amount 
of blood which is to flow to a particular organ at a par- 
ticular time. 

III. EDUCATIOK OF CORD AND BRAIN 

As the muscles can be developed by systematic exer- 
cise, so the nervous system may be cultivated and edu- 
cated. Any particular act may be very hard to perform 
at first, and may require the whole attention to perform 
it even clumsily when it is first done, but, if often re- 
peated, it may finally be done with perfect grace and pre- 
cision, wdiile one is thinking of something else. It thus 
becomes an automatic action. Methods of thought, and 
certain lines of thought, may become habitual in a meas- 
Tir^, just as combinations of motions may become habitual 
and automatic. This makes it a matter of very great 
importance for all young people to cultivate correct habits 
of action and of thought. 

3. THE HYGIENE OF THE NERVOUS SYSTEM 
I. EXERCISE AND REST 

Like all other tissues of the body, nerve tissue requires 
a certain amount of exercise and a certain amount of rest, 
if it is to be vigorous and healthy. As all of the knowledge 
which we possess comes to us through sensation, it is very 
important that the acateness of sensation be cultivated. 
This can be done only by close attention to things which 
one is observing. One should train himself to give his 
undivided attention to anything which he is observing 
with his senses. If he is studying the color and texture 
of an object through his senses of sight and touch, he 



246 PHYSIOLOGY 

should give bis undivided attention to the study. If he 
is listening to a lecture or a concert, he should give his 
undivided attention to that, thus not only cultivating a 
habit of concentration, but also cultivating the acuteness 
of the senses. At least one or two hours of intense men- 
tal activity is required each day, if the mind of a j^oung 
person is to develop a power of close application and 
correct, logical thinking. 

But tissues that work hard must also rest perfectly. 
Perfect rest of the brain can be gotten only during sleep. 
Every person should have from seven to eight hours of 
sound sleep out of every twenty-four if he is to continue 
in vigorous health throughout his allotted years. 

II. THE INFLUENCE OF ALCOHOL . 

" Alcohol acts primarily on the nerve cells, changing 
their granular matter, breaking up their nutrition, and 
changing their dynamic force. This action is followed by 
contraction of the dendrites, swelling and atrophy of these 
fibers, also shrinking of cell walls, as in fatigue, and 
coalescing and disappearance of the granular matter of 
protoplasm. "1 

"- Alcohol does not affect all the spinal cells equally, and 
in the early stages the changes are rather indefinite, a 
greater sharpness of contour being the most obvious. In 
the cerebrum the cells appear as mere shadows, both sub- 
stances disappearing, whilst the nuclei are also altered. "^ 

'' Just why the alcohol should select a set of nerves on 
which to act at one time and a different set at another 
does not at once appear, but it is a well-authenticated fact 

1 Journal of the American Medical Association, November, 1898. 

2 London Lancet, October 31, 1896, p. 1245. 



THE NERVOUS SYSTEM 247 

that it has a selective power. Most likely the explanation 
lies in the chemical or electrical condition of the white 
substance at the time of action, or it may be attributable 
to the different chemical constituents of the liquor used." ^ 

"Professor Kraepelin of Heidelberg tried a number 
of experiments on individuals, with the object of seeiiig 
wliether a small quantity of alcohol hindered the nervous 
transmission of intelligence to the brain. Flags were 
raised at a given distance, and the exact time was noted 
when the various men experimented upon observed the 
raising of the flag. The result proved that the watchers 
who had been given a small quantity of alcohol, though 
they felt that they had seen the flag rise sooner than those 
who had received no alcohol, actually took longer." 

Professor AVoodheacl says, " After careful examination 

of the whole question, physiologists — and among physi- 
ologists I include those who maintain alcohol may be 
useful, as well as those who hold that it is harmful — 
have come to the conclusion that the principal action of 
alcohol is to blunt sensation, and to remove what we may 
call the power of inhibition by blunting the higher centers 
of the brain." 

Professor David Starr Jordan in the Popular Science 
Monthly^ February, 1898, said : " The healthy mind stands 
in clear and normal relations with Nature. It feels pain 
as pain. It feels action as pleasure. The drug which 
conceals pain or gives false pleasure Avhen pleasure does 
not exist forces a lie upon the nervous system. The 
drug which disposes to reverie rather than to work, which 
makes us feel well when we are not well, destroys the san- 
ity of life. All stimulants, narcotics, tonics, which affect 
the nervous system in whatever way, reduce the truthful- 

1 Dr. Wilkins, in the New York Medical Journal, September 22, 1894. 
hall's phys. — 16 



248 PHYSIOLOGY 

ness of sensation, thought, and action. Toward insanity 
all such influences lead ; and their effect, slight though 
it be, is of the same nature as mania. The man who 
would see clearly, think truthfully, and act effectively 
must avoid them all. Emergency aside, he cannot safely 
force upon his nervous system even the smallest false- 
hood." 

Dr. Hammond said : '-'- The more purely intellectual quali- 
ties of the mind rarely escape being involved in the general 
disturbance [caused by alcohol]. The power of applica- 
tion, of appreciating the bearing of facts, of drawing dis- 
tinctions, of exercising the judgment aright, and even of 
comprehension, are all more or less impaired. The mem- 
ory is among the first faculties to suffer. . . . The will 
is always lessened in force and activity. The ability to 
determine between two or more alternatives, to resolve 
to act when action is necessary, no longer exists in full 
power, and the individual becomes vacillating, uncertain, 
the prey to his various passions, and to the influence of 
vicious counsels." 

" Helmholtz told us in his autobiography that if he took 
wine while occupied with a mathematical or scientific 
problem, his thinking powers were interfered Avith, and he 
had to wait for the alcoholic effects to work off before his 
inspiration returned." ^ 

'' Finally we have still to declare that alcohol hinders 
the action of the highest mental faculties. A remark 
made by Helmholtz at the celebration of his seventieth 
birthday is very interesting in this connection. He spoke 
of the ideas flashing up from the depths of the unknown 
soul, that lies at the foundation of every truly creative 
intellectual production, and closed his account of their 

1 Dr. Adolph Rupp, J^ew York Medical Journal, July 9, 1898. 



THE NERVOUS SYSTEM 249 

origin with these words : ' The smallest quantity of an 
alcoholic beverage seemed to frighten these ideas away.'"^ 

W. Boyd Dawkins says: ''I cannot drink beer when 
I am using my brain, and do not take it when I have 
anything to think about." ^ 

'^ Some people imagine that after the use of alcohol they 
can do things more quickly, that they are brisker and 
sharper, but exact measurement shows that they are slower 
and less accurate. Men believe that they are wiser and 
brighter, but their sayings are more automatic and apt 
to be profane. To quote Dr. Lauder Brunton, of Oxford 
University, England, '- It pi^oduces progressive, paralysis of 
the judgment^'' and this begins w^ith the first glass. Men 
say and do, even after a single glass of drink, what they 
-^would not say or do without it, and therefore it clearly 
affects the brain and diminishes self-control."^ 

Professor von Bunge,^ of Switzerland, says that, " The 
stimulating action which alcohol appears to exert on the 
brain functions is only a paralytic action. The cerebral 
functions which are first interfered with are the poiuer of 
clear judgment and reason. No man ever became witty 
by aid of spirituous drinks. The lively gesticulations and 
useless exertions of intoxicated people are due to paralysis, 
— the restraining influences, which prevent a sober man 
from uselessly expending his strength, being removed.' 

" The capital argument against alcohol, that which must 
eventually condemn its use, is this, that it tahes away all 

1 Adolph Fick, Professor of Physiology, Wurzburg, Germauy. , 

2 Quoted by Dr. M. L. Holbrook, Journal Medical Teniperaiice Associa- 
tion, January, 1898, p. 21. 

3 Dr. G. Sims Woodhead, Professor of Pathology, Cambridge University, 
England. 

4 G. Yon Bunge, Professor of Physiological Chemistry, University of Basel, 
in Text-book of Physiological and Pathological Chemistry. 



250 PHYSIOLOGY 

the reserved control^ the poiver of mastership, and therefore 
offends against the splendid pride in himself or herself which 
is fundamental in every man or woman worth anything.'' ^ 

III. THE EFFECTS OF TOBACCO UPOX BRAIN WORK 

" I have been a teacher in Connecticut twenty years. 
... In boys addicted to this (tobacco) habit I find a 
nervous irritability, and inability to do the work that 
properly belongs to boys of their age. Where the habit 
has been abandoned, I have found a marked improvement, 
both mentally and physically. "^ 

KEYIEW OF THE NERVOUS SYSTEM 

1. Before going on with this review be sure that you can answer 
the seventeen questions at the beginning of this chapter. 

2. Draw a figure of a nerve cell ; draw and describe the dendrites. 
What is the neurite ? 

3. How many kinds of tissue are there in the nervous system ? 

4. What are nerve centers? 

5. Why was nervous tissue formerly classified as " white and 
gray matter " ? 

6. Draw a figure representing a section of the spinal cord. 

7. Of how many main divisions is the brain composed ? 

8. Of what importance are the convolutions of the brain? What 
is the principal work of the Cerebrum? Of the Cerebellum? Of 
the Medulla Oblongata? 

9. How may the brain be improved? Why does the brain need rest? 

10. AVhat is the effect of alcohol upon the brain? 

11. What is the effect of tobacco upon the brains of young and 
growing persons? 

1 Dr. John Johnson, quoting Walt Whitman. 

2 Maria F. Starr, Principal High Street School, New London, Conn. 



CHAPTER XIII. —THE MUSCLES — HOW THE 
BODY MOVES 

1. THE MUSCLES: HOW THEY ARE MADE, HOW THEY 
ARE ARRANGED, AND HOW THEY WORK 

Figure 59 shows how the body would look if the skm, 
and the layer of connective tissue and fat beneath the 
skin, were all removed, leaving the muscles bare and 
open to view. Though a great number of muscles are 
..,-^^^^^^-shown in the figure, those shown are only a small propor- 
tion of all the muscles in the body ; the figure shows only 
the outside muscles. 

There are about five hundred voluntary muscles. The 
voluntary muscles are those that are under the control of 
the will ; the muscles of the legs, arms, body, neck, and 
face are all voluntary muscles. These voluntary muscles 
are, most of them, much larger than the involuntary, such 
as those in the walls of the stomach and intestines, and 
usually contract with a quicker and stronger action than 
do the involuntary muscles. 

By studying the limbs in the figure, especially the arm 
at the right, you will notice that the upper or middle 
portions of these muscles are large and full, and that from 
the largest part of the muscle it tapers down to a small 
cord at the wrist or ankle. This small cord at the 
end of the muscle is not composed of muscular tissue, 
but of very dense and inelastic connective tissue. If the 
full, round muscle extended down over the wrists and 

251 



252 



PHYSIOLOGY 




Fig. 59. — The muscular system. [Tracy.] 



THE MUSCLES 253 

ankles, it would make these as large around as the fore- 
arm or calf, and that would make the wrist and ankle 
very clumsy and awkward. 

These glistening white cords spread out into a fan 
shape at the end where the muscle attaches to it. This 
glistening white cord passes over the wrist or ankle, down 
to the hand or foot, where it is attached to the bone, and 
through this tendon the muscle can move the hands and 
feet, with their fingers and toes. Muscles are generally 
attached to the bones at each end, and use the bones as 
aids to accomplish their work. The bones serve as levers. 




Fig. 60. — The arrangement of bones and muscles by which the arm is bent : 
^,the radius; B, the elbow; (7, biceps; E, ulna; i^, triceps; G^, shoulder 
joint. 

Figure 60 shows the bones of the arm, together with 
the two most important muscles. In the position in which 
the arm is shown, the biceps muscle supports the weight 
which is resting in the hand. The bones of the forearm, 
that is, the radius and ulna, act as a lever. This lever is 
fastened at the elbow joint, that is, the elbow is the ful- 
crum of the lever. The biceps muscle represents the 
power which pulls upon the lever between the fulcrum 
and the weight resting in the hand. When the fulcrum, 



254 



PHYSIOLOGY 



the power, and the weight are arranged in this way, the 
lever is said to be one of the third order. It is easy to see 
that a slight contraction of the biceps muscle will move the 
weight a greater distance than tlie actual contraction of 
the muscle. In all levers of the third order, the weight 
moves through a greater distance than the power, that is, 
there is a gain in the distance moved by the weight, but a 
loss in power. 

Figure 61 shows the three orders of levers. In the 
lever of the first order, notice that the fulcrum is between 
the power and the weight. In the lever of the second 



V 
w 



First order. 



WT 

Second order. 






Third order. 



Fig. 61. — The three orders of levers. 



order, the weight is between the fulcrum and the power, 
while in the third order, the power is between the fulcrum 
and the weight. In the lever of the first order, the power 
will move through a greater distance than the weight, as 
long as the fulcrum is nearer to the weight than to the 
power, but when the fulcrum gets nearer to the power 
than to the weight, then the weight will move through a 
greater distance than the power. In a lever of the second 
order, the weight is always nearer to the fulcrum than 
the power is, and will, therefore, always be greater than 
the power, and will always move through a smaller dis- 
tance than the power. In the third order, the power is 
always nearer to the fulcrum than the weight is, and will, 



THE MUSCLES 255 

therefore, always be greater than the weight, and will 
move through a shorter distance than the weight. 

EXPERIMENTS AND PROBLEMS 

1. The leg of a chicken, including the toes and as much 
of the drumstick as possible, may be obtained from a 
butcher or from the kitchen. Remove the skin, and 
separate out the muscles and tendons. Notice the effect 
upon the movements of the toes when the different mus- 
cles or tendons are pulled. 

2. Refer to Figure 61. What order of lever is the 
foot when one lifts his weight upon the toes by a con- 
traction of the muscles on the back of the calf ? What 
kind of lever does the foot make when one, without 
putting the heel upon the floor, lifts a weight which 
rests upon the toes ? 

3. What kind of a lever is the low^er jaw during the 
process of chewing? What lever is the foot when one 
rests the weight of the body upon the heel ? 

4. What order of lever does one make of one's arm, if 
one takes a weight in the right hand and holds the right 
arm in such a way that the forearm will be horizontal and 
above the head ; then, holding the upper arm still, 
straightens the arm, thus lifting the weight up? Per- 
haps this problem could be understood better if you 
should turn Figure 60 upside down. 

2. THE HYGIENE OF THE MUSCLES 

From what has been said in previous lessons, you know 
that the work of the muscles consists in generating the 
heat which keeps the body warm, and also in producing 



256 PHYSIOLOGY 

the motions of the body. They produce these motions by 
shortening and thus pulling up their tendons, and moving 
the bones. The stronger the muscles, the more work 
they are able to perform, both in warming the body and 
in bodily movements. 

The first thing required by the muscles is nourishing 
food, and plenty of it. No part of the body is so sensi- 
tive to changes in the food as is the muscular system. 

I. EXERCISE AKD REST 

The muscles, like the brain and other organs, are devel- 
oped by exercise. Nearly all young animals play. Play 
is Nature's method for exercising the muscles, brain, and 
senses. One should choose for exercise those move- 
ments which require quickness and accuracy, rather than 
those which require great strength. To most people, 
calisthenics and individual gymnastics are uninteresting. 
It has been shown by years of observation on the part of 
men who have made a life study of the development of 
the nerves and muscles, that the most wholesome exercise 
is that obtained in games of skill and agility in which 
several individuals are contesting. Engaged in such a 
game, one loses all thoughts of himself and of the object 
of his exercise in his endeavors to win points in the game. 
Among the best games for the all-around development of 
the body are tennis, basket ball, hand ball, baseball, cricket, 
football, la crosse, and golf. 

One should not exercise severely within half an hour 
before a meal, or within half an hour after a light meal or 
one hour after a heavy meal. Fatigue or weariness is 
Nature's notice to take a rest. It has been stated in a 
previous lesson that when the brain and the muscles both 



THE MUSCLES 257 

call at the same time upon the circulatory system for more 
blood, the muscles will get it, and the brain will go with- 
out. For this reason, one should do his studying first, 
and his playing or work afterward. Some have not a 
choice in the matter, and are obliged to study after their 
work, if they study at all ; but if one has a choice of the 
order in which he will perform his tasks, he will be wise 
to do his brain work first, while the muscles are at perfect 
rest ; then if he goes out in the latter part of the day and 
takes vigorous muscular exercise, or does his muscular 
work, he will withdraw the excess of blood from the 
brain, thus making it easier for the brain to rest at night 
in a dreamless, restful sleep. 

II. THE EFFECT OF ALCOHOL ON THE MUSCLES 

The use of alcoholic beverages decreases the muscular 
power, as is shown by the following incident, quoted from 
the Weekly Telegraphy London, 1897: An English con- 
tractor, while erecting a large bridge in Scotland, was 
surprised at the apparent muscular power of the High- 
landers whom he engaged. Having contracted for exca- 
vating a canal in England, he engaged about twenty 
Highlanders to accompany him southward. Several 
disputes occurred between these northerners and the 
Englishmen with whom they worked upon the canal, and 
the Highlanders were made the butt of many a jeer 
relative to the simple bread and milk fare on which they 
were contented to exist, thus saving the greater part of 
their wages to bring back to their friends and families. 
To settle these disputes, a wager was made that twelve 
Highlanders could not excavate a certain number of yards 
in the same time as an equal number of the '' better fed " 



258 PHYSIOLOGY 

Englishmen. Everything being fixed, a table was laid 
out with meat and ale for the Englishmen, while the 
Scotch had, besides their bread and milk, no other prepa- 
ration for refreshment except what a can of fresh water 
afforded. But the point in dispute was, after a fatiguing 
day's work, decided in favor of the Highlanders, and 
while the Englishmen were totall}^ exhausted by their 
exercise, the Highlanders still had a good reserve of 
strength and, in their enthusiasm at their success, danced 
their national Strathspey in token of their victory. 

Dr. DeVaucleroy, Professor of Hygiene in the Military 
School of Belgium, says: "The influence of alcohol upon 
muscular work has been established permanently. It has 
been demonstrated that man works better when he does 
not use these pretended stimulants. The physiological 
experiments of Destree have established that alcohol is a 
paralyzer of muscular work. It excites at first, but this 
excitation is altogether transient, and is followed imme- 
diately by depression." 

English and American athletes have long recognized 
the very great importance on the part of those who are to 
enter contests, of total* abstinence during the period of 
training as well as during the period of contest. Nearly 
ten years ago this began to be recognized among the 
German university students, and one club after another 
abandoned the morning drinking bout in order to better 
fit themselves for athletic contests in wliich their members 
wished to take part. 

Dr. Charles Stewart says* that, " In a number of experi- 
ments carried out with the idea of ascertaining the effect 
of alcohol upon muscular force, it was found that in every 
case where alcohol was taken, muscular force was dimin- 
ished, even when so small an amount as one half dram 



THE MUSCLES 259 

(one half a teaspoonful) of alcohol was used. In these 
experiments it was found that nonabstainers were affected 
as well as abstainers. The deceptive nature of alcohol 
was manifested in every case, each individual feeling sure 
that he could accomplish more than he could before 
taking the alcohol. "^ 

Many hundreds of similar experiments might be cited, 
but they all demonstrate the same thing^ namely^ that the 
use of alcohol decreases the force and efficiency of the 
muscular system. 

ALCOHOL AS AN ARMY RATION 

"The uselessness, if not the harmfulness, of even moder-- 
ate doses of alcohol rests on better evidence than scientific 
deduction and experiments. In connection with the sani- 
tation of armies, thousands of experiments upon large 
bodies of men have been made, and have led to the result 
that, in peace and war, in every climate, in heat, cold, and 
rain, soldiers are better able to endure the fatigues of the 
most exhausting marches when they are not allowed any 
alcohol. A similar result is observed in the case of the 
navies and on thousands of commercial vessels belonging to 
England and America, which put to sea without a drop of 
alcohol. Most whalers are manned by total abstainers." ^ 

In a paper entitled " War's Aftermath," in the May 
Forum^ 1899, Mr. W. K. Rose, Renter's correspondent in 
the Soudan campaign, said : '' Alcoholic drinks are, how- 
ever, now eschewed by the best commanders. ' Havelock's 
saints ' performed their heroic feat in marching and fight- 
ing in the Indian mutiny on coffee alone as a beverage. 

1 Journal of the Medical Temperance Association, January, 1897, p. 54. 

2 Professor Bunge. 



260 PHYSIOLOGY 

In the Red River expedition of 1870, under General 
Wolseley, no spirit ration was issued ; and certainly, says 
the Medical Report^ no men could have enjoyed better 
health than did the troops without it. Out of the seven 
hundred and ten men engaged only five were invalided. 
The old-fashioned rum ration was not issued in the Ashan- 
tee War of 1873, — which was also under the command of 
General Wolseley, — though a small amount was given 
to individuals when especially prescribed by the medical 
officers. The result was that, in the pestilential climate 
of the hinterland of the Gold Coast, the total mortality 
from all causes was only 3.14 per cent of the whole 
strength of the British troops. In the Kaffir War of 
1877-1878 rum as a ration was strictly prohibited; and 
the good health of the troops was attributed to enforced 
abstinence from spirituous liquors." 

Colonel Geary, in a paper before the Sanitary Con- 
gress at Stafford, stated that during the Abyssinian cam- 
paign, for six weeks advancing upon and retiring from 
Magdala, there was no alcohol, no crime, and the per- 
centage of sick was less than in any part of the British 
army at home or abroad, while the troops performed 
arduous marches on scanty food and often with bad water. 

Lord Roberts, the commander in the Boer campaign, 
says that the effective strength of an army is always 
proportionately greater according to the number of total 
abstainers in the ranks. 

'' To-day it is a great feather in the headgear of the 
advocates of military total abstinence that Lord Kitch- 
ener's recent victory was won for him by an army of tee- 
totalers, who made phenomenal forced marches through 
the desert, under a burning sun, and in a climate famed 
for its power to kill or prematurely age the unacclimated. 



THE MUSCLES 261 

Indeed, it is said that never has there been a British cam- 
paign occasioning so little sickness and profiting by so 
much endurance."^ 

ALCOHOL A CAUSE OF MENTAL DISORDERS 

" If you look round and try to find out the primary 
causes of disease and poverty and crime and misery, you 
are over and over again thrown back on the use of 
alcohol. One cannot read the newspapers and reports 
of judges without seeing that alcohol accounts for a very 
large proportion of what is evil in our daily life. It is 
sapping the foundation of our national life, and if we 
could do away with all the disease and poverty and crime 
caused by alcohol, the questions which confront us would 
be solved very easily." ^ 

THE INFLUENCE OF ALCOHOL UPON THE MORALS 

"The most highly specialized characteristics are first 
impaired, and thus the spiritual faculty, if I may so term 
it, first becomes blunted by the use of alcohol. Follow- 
ing this in rapid succession there is blunting of the moral 
sense ; a slight, though distinctly perceptible, interference 
with the intellectual faculties, which leads to what we 
might call blurring of the reasoning poAver ; then follows 
a distinct diminution in the power of rapidity and accuracy 
of perception. At none of these stages would a man admit 
that he was under the influence of alcohol ; but these 
powers are just as assuredly under its influence as are the 
muscles which can no longer act coordinately to enable a 
man to walk straight."^ 

^ Washington Star. ^ Professor G. Simms Woodhead. 

3 Professor Woodhead. 



262 PHYSIOLOGY 

'^Tlie nervous system cannot escape injury from the 
ingestion of alcoholic drinks. It fails to receive correct 
impressions ; it fails to send out correct orders ; it fails 
to receive proper rest. . . . The continued use of alcohol 
causes the nervous centers to undergo degeneration, and 
the most serious diseases known to medical science ensue." ^ 

1 George H. McMichael, M.D., Buffalo, N.Y. 



CHAPTER XIV. — THE SKELETON — THE 
FRAxMEWORK OF THE BODY 

The earthworm has no framework ; he cannot hold his 
body erect, all of his movements must be slow and grovel- 
ing. Tlie butterfly has a framework. Portions of this 
framework support the delicate, membranous wings, whose 
framework is articulated to the body. Through the aid 
of muscles which pass from the body to the framework of 
the wings, these may be moved, and enable the butterfly 
to fly out into the sunshine. 

Man's body has a framework, — the bony skeleton, the 
parts of w^hich lie deeply buried in the muscles. Without 
this framework man could not stand erect. ■ The skeleton 
of man is very much like the skeleton of other vertebrate 
animals. All vertebrate animals possess a vertebral col- 
umn^ tvhich is called the axis of the body. 

When the dog or cat is standing on all fours, his verte- 
bral column is horizontal, and his four legs pass dowmward 
to the ground as supports. The four legs of the dog or eat^ 
together with the large flat bones which fasten them to the 
vertebral column, are called the appendages of the body 
axis, or the appendicular system. The axis of the body 
comprises not only the vertebral column, but the skull, 
as well as the ribs and sternum. The axis, or vertebral 
column, of the cat or dog is extended backw^ard beyond 
the body, the bones getting smaller and smaller clear to 
the tip of the tail. In the case of man and of the higher 
apes, the axis, or vertebral column, does not extend be- 
hall's phys. — 17 263 



264 



PHYSIOLOGY 



yond the body, but the last few bones of the vertebral 
column are grown together into what appears, at first, to 
be one large, strong bone, called the sacrum, beyond which 

is a little bone called the coccyx. 
Figure 62 gives a side view of 
the vertebral column, and shows 
the curved sacrum at the bottom, 
composed of live vertebrae joined 
together. At the end of the 
sacrum there is the little coccyx 
of four buttonlike bones, usually 
grown together. 

PROBLEMS 

1. To what part of your body 
does the paw of a cat correspond ? 

2. Find upon a cat's body the 
part which corresponds to your 
elbow. 

3. Find the part which corre- 
sponds to your knee. 

4. Find the part which corre- 
sponds to your heel. 

5. Find upon a horse's body 
the part which corresponds to 
your elbow. 

6. To what part of your body 
does what we call the horse's 
knee correspond ? 

7. To what part of your body does the horse's hoof 
correspond ? 

8. To Avhat part of the horse's body does your heel 
correspond ? 




THE SKELETON 265 

9. Observe a dressed chicken, and find upon the 
chicken the part which corresponds to your knee ; the 
■part which corresponds to your heel. 

10. Find the part which corresponds to your elbow ; to 
your wrist ; to your fingers. 



1. THE HUMAN SKELETON 
I. HOW THE BONES ARE GROUPED 

Figure 63 gives a front view of the human skeleton. 
Notice that the first, or upper, joint of the arms has one 
bone, the humerus ; and that the corresponding joint of the 
legs has one bone, the femur. Notice, further, that the 
second joint of the arm corresponds to the second joint of 
the leg in having two bones. The third joint, or third 
portion of the anterior limb, comprises the wrist and five 
digits ; while in the leg, the corresponding portion com- 
prises the ankle and five digits. Notice that the arms are 
held in place by two large flat bones back of the ribs, 
called the shoulder blades^ and that the shoulder joint is 
braced in front by the coUa?' hones^ which pass from the 
shoulder blade to tho sternum. The humerus is joined to 
the scapula with a hall and socket joint., the ball on the 
end of the humerus fitting into a spherical socket in the 
shoulder blade. In a similar way, the legs are attached 
to the axial skeleton through two large, flat, irregular 
bones called the innominate hones. The innominate bones 
are firmly joined to the sacrum behind, and firmly united 
together in front. This makes a strong basinlike founda- 
tion for the whole body, called the pelvis. The leg bones 
are joined to the pelvis by a ball and socket joint ; the 
other joints of the limbs are hinge joints. 




Fig. 63. — The skeleton. 



THE SKELETON 267 

Count up the bones of the skeleton, and see how many 
you can find. Not counting the teeth and the six little 
ear bones, the skeleton is composed of two hundred bones. 
Turning again to Figure 62, notice that the spinal column 
shown there was sawed through the middle. This shows 
the canal which passes up through the spinal column, and 
within wliich the spinal cord lies. The cord is thus 
thoroughly protected from harmful pressure or injury. 
Similarly the brain is always thoroughly protected within 
the bony cranium which rests upon the top of the spinal 
column. 

In Figure 62 there seems to be space between the ver- 
tebrae. These spaces are filled in the living body with a 
firm, elastic cartilage^ which gives sufficient opportunity 
for the bending of the spine, and serves a most important 
purpose as a series of cushions, which protect the brain 
from the jarring it would otherwise suffer when one 
walked or jumped on hard ground. 

II. HOW^ THE BOXES ARE MADE 

Figure 64: shows the femur as it appears when sawed in 
two, lengthwise. Notice that the two ends of the bone 
are larger than the shafts and that they seem to be made 
differently inside. At the two ends of the bone we find 
what is called cancellous tissue. It is made \\^ of little, 
thin, bony plates so joined together as to make a very 
great number of little compartments with thin, bony 
walls. The little spaces within these boiiy cells are filled 
with blood vessels and a tissue which is something like 
gland tissue. This portion of the bones and similar tissue 
wherever found in the body, especially within the ribs 
and in the heads of the long bones, is called red marrow 



268 



PHYSIOLOGY 



and is the place where red blood corpuscles are formed. 

The shaft of the bone is occupied by a very few blood 
vessels, all the rest of the space 
being filled with a deposit of 
fat, giving the cut bone a yellow 
appearance. This portion of the 
bone marrow is called the yellow 
marrow. 

In infancy the bones are very lim- 
ber and may be easily bent, because 
they are composed mostly of cartilage 
or gristle. As the child advances 
in age, the bones get stronger and 
stronger owing to a deposit of lime 
wathin the bone tissue. If one takes 
a chicken bone and soaks it in acid, 
especially diluted hydrochloric acid, 
he will find that the bone will grad- 
ually get softer and softer until it is 
limber enough to tie into a knot. 
This change in the bone is due to 
the mineral matter of the bone being 
dissolved out. 

On the other hand, if one puts a 
bone into a fire and burns it until it 
bouy fibers at the upper ig white, thus burning out all of the 

end, its peculiarity be- . . . i -ri ^ j i. i. 

animal matter, he Avill iina when he 




Fig. 64. — The right femur, 
or thigh bone, sawed in 
two lengthwise. Notice 
the arrangement of the 



ing somewhat exagger- 
ated so as to make it 
more plain. [Tracy.] 



takes it out of the fire that it is 
brittle and can be crushed in the 
fingers. These two experiments teach us that a bone gets 
its stiffness and hardness from the mineral matter and its 
toughness and flexibility from the animal matter which it 
contains. 



THE SKELETON 



269 



III. HYGIENE OF THE BONES 

From what has been said above it is evident that the 
bones of growing children need mineral matter, and it is 
further evident that this mineral matter must come through 
the food. Nature's food for infants (milk) contains the 




Fig. 65. — A represents the normal appearance of the ribs. B represents part 
of a photograph of the skeleton of a young woman of twenty-three years, 
showing the distortion of the ribs produced by tight lacing. [Tracy.] 



mineral matter in sufficient quantity and in proper propor- 
tions. After the young child stops making milk its only 
diet, its food must be chosen with some care in order to 
provide it with plenty of bone-making material. The 
cereal foods and the vegetables are the best for this pur- 
pose. 

The bones of young people and children are very easily 



270 PHYSIOLOGY 

distorted or bent out of their proper shape because they 
have not yet become stiff and hard through the mineral 
matter, so it is important that little children in schools or 
at home should not sit on high seats where the weight of 
the lower legs and feet hangs from the end of the femur, 
which rests upon the edge of the seat. Such treatment of 
the femur would bend it out of its natural shape. 

Children and young people should take great care to 
hold their bodies erect when sitting, standing, walking, or 
riding. This requires some effort and attention, but if it 
is done faithfully, one not only gets a habit of erect car- 
riage, but one's bones and muscles later naturally assume 
these positions, thus giving a person a much more dignified 
and stately bearing than would otherwise be possible. 
Figure 65 should be a striking object lesson for those who 
are inclined to wear clothing too tight to give perfectly 
free movements for the thorax. In the figure at the 
right, the vital organs, such as the lungs, heart, stomach, 
liver, spleen, and pancreas, are all crowded into much nar- 
rower space than they are intended by Nature to occupy. 
This hinders them from doing their best work, and as 
they are the organs which provide for the general nutri- 
tion of the whole system and all the vital processes, it 
must be evident that the health of an individual whose 
chest is thus permanently deformed will sooner or later 
be very seriously interfered with. 



INDEX 



Absorption of food, 197. 

Adam's apple, 168. 

Air, changes in lungs, 179; comple- 
mental, 173 ; composition of, 178 ; 
impure, 186; reserve, 173; residual, 
173; tidal, 172. 

Alcohol, effects of, upon blood, 159; 
blood corpuscles, 191; on digestion, 
115; on heart, 159; on liver and 
kidneys, 210; on muscles, 257; in- 
fluence of, general, 69; on nervous 
system, 246; on skin, 219; how 
formed , 59 ; not a food, 110 ; relation 
to animal heat, 191 ; relation to lung 
diseases, 192. 

Alimentary canal, 89. 

Amoeba, one-celled animal, 34. 

Apples, acid fruits, 87. 

Arteries, 136, 138. 

Automatic action, 55. 

Barley, a cereal, 81. 

Bathing, 217. 

Bicuspid teeth, 91. 

Bleeding, protection of body against, 
131, 143. 

Blood, 128; changed in lungs, 180; 
coagulation of, 131 ; condition of, 158 ; 
freed of carbon dioxide, 182 ; figured 
and described, 129; nourishes tis- 
sues, 144 ; oxygenated, 180 ; gives up 
oxygen, 146. 

Body heat, 184. 

Bones, 263, 265, 267. 

Brain, 238, 241, 243; education of , 245; 
influenced by tobacco, 250. 

Breathing, chest and abdominal, 174; 
forced, 172. 

Bronchi, 168. 



Caecum (se^cum) , 90. 
Canine teeth, 91. 



Capillaries, 139, 147. 

Cardia of stomach, 93. 

Cartilage, figure and description, 39. 

Cell, described, 30; diagram of, 29; 

lymph, 30; of plant, 30; plasm, 30; 

vrork of, 28. 
Cells, review of, 45 ; of body, 27. 
Cereals, defined and described, 81; 

experiments with, 83. 
Chyle, 150. 
Circulation, control of, 151; diagram 

of, 140 ; review of, 162. 
Circulatory system, 42. 
Clothing, 218; effect of, on skeleton, 

270. 
Coagulation of blood, 131. 
Colon, 90. 

Colony animal, 38; plant, 37. 
Complemental air, 173. 
Constrictors of blood vessels, 154. 
Corn, plants, 12 ; a cereal, 81 ; kernels, 

11. 
Coughing, 175. 
Crying, 176. 
Cuticle, 213. 

Desmids, one-celled water plants, 
33. 

Diaphragm, 167. 

Digestion by gastric juice, 99 ; hygiene 
of, 104 ; by pancreatic juice, 101 ; by 
plants, 21 ; by saliva, 97 ; review, 
103. 

Digestive system, 42 ; figure of, 90, 91 ; 
review of, 96 ; structure of, 89. 

Dilators of blood vessels, 154. 

Distillation, described, 61. 

Domestic Economy, 118. 

Drinks, alcoholic, 110 ; hygiene of, 107 ; 
narcotic, 58 ; nourishing, 110 ; re- 
freshing, 109; stimulating, 110. 

Duodenum {du-o-de'-num) , 89, 95. 



271 



272 



PHYSIOLOGY 



Ear, description of, 22S; hygiene of, 

230. 
Economy, domestic, 118. 
Eggs, 78. 

Energy of life, generation of, 203. 
Epidermis, 212, 213. 
Esophagus, 89. 
Excretion by kidneys, 207. 
Exercise, 155 ; and rest, 256. 
Experiments, in plant physiology, 21 ; 

in respiration, 189; on cereals, 83; 

on foods, 80 ; on vegetables, 8G ; with 

gastric juice, 100; with pancreatic 

juice, 102; with saliva, 98. 
Expiration, 1G(3, 172, 173. 
Eye, description of, 233; hygiene of, 

231. 

Ferment, defined, 22. 

Fermentation, 61, 63. 

Fevers, 185. 

Food, how used in body, 196; absorp- 
tion of, 197. 

Foods, 78; experiments on, 80, 83, 86; 
review of, 89. 

Fruit, 86: juices and sirups, 109. 

Gastric juice, digestion by, 99. 
Germ of plant, 20. 
Gland, described, 42. 

Habit, 55, 57. 

Hair, 212. 

Harmony of work, nervous system, 46. 

Hearing, sense of, 228. 

Heart, 133, 131, 139. 

Heat of body, 183. 

Hiccoughing, 176. 

Hygiene, defined, 9; of bones, 269; of 
circulation, 155 ; of digestion, 104 ; of 
ear, 230; of eye, 234; of kidneys, 
208; of liver, 208; of muscles, 255; 
of respiration, 186; of skin, 216. 

Ileum {iVe-um), 89. 
Incisor teeth, 91. 
Inspiration, 166, 172. 
Intestines, 89, 95, 96. 
Iodine, test for proteid, 21; test for 
starch, 21. 

Jejunum (Je-jw'nwm), 89. 



Kidneys, description of, 207, 208. 

Lacteals, 150. 

Larynx, 168. 

Laughing, 176. 

Legumes as food, 84. 

Lemonade, 109. 

Lemons, acid fruits, 87. 

Levers, 253. 

Liver, 90; description of, 200; hygiene 

of, 208. 
Lung capacity, 174. 
Lungs, 167, 169. 
Lymph and lymphatics, 147, 148. 

Massage, 156. 

Meat, as food, 87. 

Menus, typical, plain, 88 ; typical, with 

price, 124. 
Milk, 78. 
Molar teeth, 91. 
Muscles, 251, 252; experiments, 255; 

hygiene of, 255. 

Narcotic drinks, general effect of, 65. 

Narcotics, 58; effect of on respiration, 
191 ; review of , 74. 

Nerve, cells, 238, 239; centers, 240; 
trunks, 240. 

Nervous system, 46, 48, 50, 57, 237; 
hygiene of, 245; influenced by alco- 
hol, 246 ; review, 250. 

Nucleolus of cell, 30. 

Nutrition, defined, 76. 

Oats, a cereal, 81. 

Opium, 72. 

Oranges, acid fruits, 87. 

Organs, defined and described, 40 ; of 

body, 27 ; of plant, 17 ; systems of, 

42, 43. 
Oxidation, defined, 15. 

Pancreas {pdn'kre-ds) , 90, 95. 
Pancreatic juice, digestion by, 101. 
Papilla, of skin, 212; tactile, 220; 

vascular, 220. 
Parotids {pa-rot'lds) , 90. 
Pharynx, 168. 
Physiology, defined, 9, 10 ; general, 11 ; 

special, begins, 75. 



INDEX 



273 



Plant, needs of, 11 ; parts of, IG ; physi- 
ology, 1), 11. 

Plants, relation of, to animals, 26. 

Plumule of plant, 20. 

Problems in domestic economy, 123, 
125 ; in respiration, 190 ; on skeleton, 
204. 

Proteid, iodine test for, 21. 

Protococcus, green dust plant, 33. 

Protoplasm of plant, 17. 

Pulse, 143. 

Pylorus of stomach, 93. 

Radicle of plant, 20. 

Rectum, 90. 

Reflex action, 52. 

Residual air, 173. 

Respiration, defined, 164, 165; exter- 
nal, 166; hygiene of, 186; internal, 
166 ; organs of, 166, 167 ; movements 
of, 170 ; review, 193. 

Respiratory system, 42. 

Rest and exercise, 256 ; time for, 157. 

Rice, a cereal, 81. 

Rye, a cereal, 81. 

Saliva, digestion by, 97. 

Salivary glands, 90. 

Seeing, sense of, 230. 

Sensation, function of skin, 216. 

Sensations, described, 54. 

Sense, of hearing, 228 ; of position, 222 ; 
of seeing, 230 ; of smell, 226 ; of taste, 
225; of temperature, 221; of touch, 
220. 

Senses, general and special, 220; re- 
view of special, 236. 

Sighing, 176. 

Skeleton, 263, 266 ; affected by tight 
clothing, 270 ; problems on, 264. 

Skin, description of, 212; hygiene of, 
216 ; organ of sensation, 219 ; review 
of, 223. 

Smell, sense of, 226. 

Sneezing, 176. 

Sobbing, 176. 

Soda water, 109. 

Speech, 177. 



Spinal cord, 241, 242. 
Spirits, ardent, 62. 
Starch, iodine test for, 21. 
Stentor, one-celled animal, 36. 
Stomach, 89, 90, 93, 94. 
Sublinguals {suh-lin'gwdls) , 90. 
Submaxillaries (sub-mdx'il-ld-ries) , 

90. 
Sweat glands, 212. 
Sympathetic nervous system, 51. 
System, circulatory, 42; digestive, 42 ; 

respiratory, 42. 

Taste, sense o|, 225. 

Teeth, 91, 92. 

Temperature, sense of, 221. 

Tidal air, 172. 

Tissue, defined, 39. 

Tissues, active, 16 ; of body, 27 ; review 

of, 45; supporting, 16. 
Tobacco, 71 ; effects of, on heart, 161 ; 

on brain work, 250 ; influence of, on 

respiration, 193. 
Touch, sense of, 220. 
Trachea, 167. 

Valves of veins, 139. 

Vegetables, as food, 84; experiments 

with, 86. 
Veins, 139. 
Vena cava, 140. 
Ventilation, 187. 
Vertebral column, 263, 264. 
Villi of intestine, 95. 
Villus, organ of absorption, 199. 
Vocal cords, 168. 
Voice, 175, 176. 
Voluntary action, 52. 
Vorticella, one-celled animal, 36. 

Waste matter , how thrown out of body, 

206. 
Water, as drink, 107. 
Wheat, a cereal, 81. 
Windpipe, 167. 

Yawning, 176. 

Yeast plant, described, 59, 



Typography by J. S. Gushing & Co., Norwood, Mass., U.S.A. 



Text- Books in Physical Training 



BLAIKIE'S SOUND BODIES FOR OUR BOYS AND GIRLS 
By William Blaikie, author of " How to Get Strong and 
How to Stay So." Cloth, i6mo ..... 40 cents 
A manual of simple, practical exercises for the training and develop- 
ment of the body so as to leave no muscle undeveloped. Numerous 
illustrations are given to make the directions for the various exercises 
clear and practical. The exercises are free from risk and can be easily 
learned. They can be practiced in the schoolroom in the brief intervals 
between the recitations under the eye and direction of the teacher without 
any loss of time. While the pupils are making progress in their studies 
they are at the same time building and strengthening their bodies and 
by so doing secure both bodily vigor and sound health. 

MORRIS'S PHYSICAL EDUCATION 

By R. Anna Morris. Cloth, 8vo $1.00 

A system of exercises including the Delsartean principles of execu- 
tion and expression, for use in schools. Each exercise and drill 
prescribed can be practiced in any school, and the few pieces of appa- 
ratus suggested are simple and inexpensive. Part I describes general 
positions and drills, and furnishes graded instruction for the development 
for each part of the body. Part II treats of the subject of expression 
as applied to reading, articulation, and declamation. Musical selections 
are given to accompany the physical exercises, and appropriate illustra- 
tions are added to indicate the movements and positions described. 

SMART'S MANUAL OF SCHOOL GYMNASTICS 

By James H. Smart. Revised and Enlarged . 30 cents 

Consisting of free gymnastics, dumb-bell exercises, and aesthetic 
exhibition exercises, so planned as to develop every part of the 
body. Movements are provided for standing positions, sitting positions, 
breathing and vocal exercises, dumb-bell exercises, military movements, 
and exhibition figures. The book is fully illustrated, and includes a 
number of musical selections to accompany the gymnastic exercises. 



Copies of any of the above books will be sent, prepaid, to any address 
on receipt of the price by the Publishers: 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(153) 



STORER AND LINDSAY'S 

Elementary Manual of Chemistry 

By F. H. STORER, S.B., A.M., and W. B. LINDSAY, A.B., B.S. 
Cloth, 12mo, 453 pages. Illustrated. Price, $1.20 

This work is the Hneal descendant of the ** Manual of 
Inorganic Chemistry" of Eliot and Storer, and the ^^ Ele- 
mentary Manual of Chemistry " of Eliot, Storer and Nichols. 
It is in fact the last named book thoroughly revised, 
rewritten and enlarged to represent the present condition 
of chemical knowledge and to meet the demands of American 
teachers for a class book on Chemistry, at once scientific 
in statement and clear in method. 

The purpose of the book is to facilitate the study and 
teaching of Chemistry by the experimental and inductive 
method. It presents the leading facts and theories of the 
science in such simple and concise manner that they can 
be readily understood and applied by the student. The 
book is equally valuable in the classroom and the laboratory. 
The instructor will find in it the essentials of chemical 
science developed in easy and appropriate sequence, its 
facts and generalizations expressed accurately and scientifi- 
cally as well as clearly, forcibly and elegantly. 



" It is safe to say that no text-book 
has exerted so wide an influence 
on the study of chemistry in this 
country as this work, originally 
written by Eliot and Storer. Its 
distinguished authors were leaders 
in teaching Chemistry as a means 
of mental training in general edu- 
cation, and in organizing and per- 
fecting a system of instructing 
students in large classes by the 
experimental method. As revised 
and improved by Professor Nichols, 
it continued to give the highest 
satisfaction in our best schools and 
colleges. After the death of Pro- 
fessor Nichols, when it became 



necessary to revise the work again. 
Professor Lindsay, of Dickinson 
College, was selected to assist Dr. 
Storer in the- work. The present 
edition has been entirely rewritten 
by them, following throughout the 
same plan and arrangement of the 
previous editions, which have been 
so highly approved by a generation 
of scholars and teachers. 

" If a book, like an individual, 
has a history, certainly the record 
of this one, covering a period of 
nearly thirty years, is of the highest 
and most honorable character." 
— From The American Journal of 
Science. 



Copies of this book will be sent prepaid to any address^ on receipt o/ the price^ 
by the Publishers : 



New York 

(i6i) 



American Book Company 

♦ Cincinnati ♦ 



Chicago 



Burnet's Zoology 

FOR 

HIGH SCHOOLS AND ACADEMIES 

BY 

MARGARETTA BURNET 

Teacher of Zoology, Woodward High School, Cincinnati, O, 

Cloth, 12mo, 216 pages. Illustrated. Price, 75 cents 



This new text-book on Zoology is intended for classes 
in High Schools, Academies, and other Secondary Schools. 
While sufficiently elementary for beginners in the study it is 
full and comprehensive enough for students pursuing a 
regular course in the Natural Sciences. It has been prepared 
by a practical teacher, and is the direct result of school-room 
experience, field observation and laboratory practice. 

The design of the book is to give a good general knowl- 
edge of the subject of Zoology, to cultivate an interest in 
nature study, and to encourage the pupil to observe and to 
compare for himself and then to arrange and classify his 
knowledge. Only typical or principal forms are described, 
and in their description only such technical terms are used 
as are necessary, and these are carefully defined. 

Each subject is fully illustrated, the illustrations being 
selected and arranged to aid the pupil in understanding the 
structure of each form. 



Copies of Burnet's School Zoology will be sent prepaid to any address^ 
on receipt of the price ^ by the Publishers: 

American Book Company 

New York ♦ Cincinnati # Chicago 

(165) 



Biology and Zoology 



DODGE'S INTRODUCTION TO ELEMENTARY PRACTICAL 
BIOLOGY 

A Laboratory Guide for High School and College Students. 
By Charles Wright Dodge, M.S., Professor of Biology 
in the University of Rochester . . . . . . $1 80 

This is a manual for laboratory work rather than a 
text-book of instruction. It is intended to develop in the 
student the power of independent investigation and to 
teach him to observe correctly, to draw proper conclusions 
from the facts observed, to express in writing or by means 
of drawings the results obtained. The work consists 
essentially of a series of questions and experiments on 
the structure and physiology of common animals and 
plants typical of their kind — questions which can be 
answered only by actual investigation or by experiment. 
Directions are given for the collection of specimens, for 
their preservation, and for preparing them for examination; 
also for performing simple physiological experiments. 

ORTON'S COMPARATIVE ZOOLOGY, STRUCTURAL AND 
SYSTEMATIC 

By James Orton, A.M., Ph.D., late Professor of Natural 
History in Vassar College. New Edition revised by 
Charles Wright Dodge, M.S., Professor of Biology in 

the University of Rochester $1.80 

This work is designed primarily as a manual of 
instruction for use in higher schools and colleges. It 
aims to present clearly the latest established facts and 
principles of the science. Its distinctive character con- 
sists in the treatment of the whole animal kingdom as a 
unit and in the comparative study of the development and 
variations of the different species, their organs, functions, 
etc. The book has been thoroughly revised in the light 
of the most recent phases of the science, and adapted to 
the laboratory as well as to the literary method of teaching. 



Copies of either of the above books will be sent, prepaid, to any address 
on receipt of the price. 

American Book Company 

New York ♦ Cincinnati ♦ Chicago 

(167) 



Gray's Series of Botanies 

By the late Asa Gray, LL.D., of Harvard University 



FOR ELEMENTARY AND GRAMMAR SCHOOLS 

Gray's How Plants Grow. With a Popular Flora . . $0 80 
A simple introduction to the study of Botany. 

Gray's How Plants Behave. A Botany for Young People . .54 
A primary book showing how plants move, climb, act, etc. 

FOR SECONDARY SCHOOLS 

Gray's Lessons in Botany. Revised edition . . . .94 

Gray's Field, Forest, and Garden Botany. New edition, 

containing Flora only ....... 1.44 

Gray's School and Fie'd Book of Botany. Comprising the 

** Lessons '* and '* P'ield, Forest, and Garden Botany/' 1.80 
A complete book for school use. 

FOR COLLEGES AND ADVANCED STUDENTS 

Gray's Manual of Botany. Revised, containing Flora only. 

For the Northern United States, east of the Missisippi, 1.62 
The Sanne. Tourist's edition. Thin paper, flexible leather, 2.00 
Gray's Lessons and Manual of Botany, One volume. Revised, 

comprising the * 'Lessons in Botany " and the ' * Manual,'* 2.16 
Gray's Botanical Text-Book 

I. Gray's Structural Botany 2 00 

IL Goodale's Physiological Botany .... 2.00 

FOR WESTERN STUDENTS 

Coulter's Manual of the Botany of the Rocky Mountains . 1.62 
Gray and Coulter's Text-Book of Western Botany. Com- 
prising Gray's "Lessons" and Coulter's "Manual of 
the Rocky Mountains " . . . , . ,2.16 



Copies of any of the above books will be sent, prepaid, to a7iy add7'ess 
on receipt of the pHce by the Publishers : 

American Book Company 

NEW YORK ♦ CINCINNATI ♦ CHICAGO 

(171) 



NOV. 6 1900 



LIBRARY OF CONGRESS 




005 526 647 




